Coated granular pesticide method for producing the same and applications thereof

ABSTRACT

A coated granular pesticide comprising a granular pesticide for use on plants which comprises at least one hardly water-soluble active ingredient and at least one water-swelling substance, and a thermoplastic resin-based film which covers the surface of the granular pesticide; a method for producing the same; and applications thereof. A surfactant, inorganic powder insoluble or hardly soluble in water, water-absorbing and/or water-soluble polymer fine powder, a thermosetting resin, or a biodegradable polymer insoluble or hardly soluble in water, or a combination thereof may be incorporated into the film. The coated granular pesticide can externally release the hardly water-soluble active ingredient due to the combined effects of the thermoplastic resin as the film-forming component and the water-swelling component as the core component whereby the water-swelling substance absorbs the water present in the exterior of the coated granular pesticide, which gradually penetrates into the granule through the coating film.

TECHNICAL FIELD

The present invention relates to a timed-release type or controlledrelease type pesticide. More specifically, the present inventionpertains to a coated granular pesticide comprising a granular pesticidewhich comprises a hardly water-soluble active ingredient and awater-swelling substance and whose surface is covered with afilm-foaming material comprising a thermoplastic resin as a principalcomponent, a method for producing the same and a method for using thecoated granular pesticide.

BACKGROUND ART

The use of insecticides, fungicides or herbicides has been indispensableto the cultivation of field crops. When applying a pesticide, it ispreferably applied in a large amount at a time from the viewpoint of thereduction of labor required for the application thereof, but suchapplication suffers from various problems such that crops and humanbodies are damaged by such a high concentration of the activeingredient, that the active ingredient is lost through washing away andthat the duration of the efficacy thereof is correspondingly reduced.

In case of the crops which require the transplantation of the seedlingsuch as those represented by paddy rice, they are damaged upontransplantation, for instance, by cutting of hair-roots and breakage ofthe seedlings. Moreover, the seedlings after the transplantation are inan unstable state till complete rooting thereof because of the greatdifference between the environmental conditions of nursery beds andfinal fields. For this reason, the application of a pesticide possessinga herbicidal action at this stage may bring about hypotrophy andwithering of seedlings due to its phytotoxity.

If a pesticide such as a herbicide may be applied to seedlings whentransplanting the seedlings, the labor required for farm working caneffectively be reduced. In case of paddy rice, however, any herbicidecan be applied thereto only after the complete rooting of the seedlings,i.e., after the lapse of about one week from the transplanting theseedlings, under the existing circumstances.

There have been known a variety of sustained release pesticides whichare developed for eliminating such drawbacks and are so designed thatactive ingredients are gradually released from those applied to fields.

Japanese Patent Laid-Open Publication (JP-A) 286602/1990 discloses agranular controlled release pesticide which comprises mineral particlesimpregnated with a liquid active ingredient and hydrophobic fineparticles which cover the surface of the mineral granules. However, thecontrolled release pesticide initiates the release of the activeingredient thereof immediately after the application thereof to fieldsand accordingly, it is not suitably applied to fields during thetransplantation of seedlings.

Japanese Examined Patent Publication (JP-B) 5002/1989 discloses asustained release pesticide which comprises a water-soluble or volatileactive ingredient covered with a thermoplastic resin. In the controlledrelease pesticide, the active ingredient is released through thethermoplastic resin film. Therefore, this technique is suitable forwater-soluble or volatile active ingredients, but it is difficult toapply the technique to hardly water soluble active ingredients. Ingeneral, most of the active ingredients used in herbicides are hardlysoluble in water and if these active ingredients are covered with thefilms disclosed in JP-B 5002/1989, the resulting pesticide suffers fromsuch problems that a desired herbicidal effect cannot be expectedbecause of its extremely low release rate and that the active ingredientremains in the soil even after the harvesting of crops to thus causecontamination of the soil therewith.

JP-A 9304/1994 and JP-A 72805/1994 disclose timed-release, controlledrelease type pesticides, in which a part of the coating film isdissolved, after the application thereof to fields, to form openingsthrough which the active ingredient is released. Moreover, JP-A9303/1994 and JP-A 80514/1994 also disclose timed-release, controlledrelease type pesticides, in which the active ingredient is releasedthrough cracks formed, after the application thereof to fields, on apart of the coating film. In these timed-release, controlled releasetype pesticides, however, the timed-release characteristics are achievedby the use of a coating film having a double layered structure and themethod for the production thereof requires complicated steps and theresulting product is expensive. Moreover, since the active ingredient isreleased through small openings or cracks formed on the film, therelease rate thereof is show and thus it is difficult to apply thesetechniques to hardly water-soluble active ingredients.

The present invention intends to eliminate the foregoing drawbacksassociated with the existing controlled release pesticides andaccordingly, it is an object of the present invention to provide acoated granular pesticide which does not release any active ingredientimmediately after the application thereof to fields and initiates therelease of the active ingredient after the lapse of a desired period oftime and which can complete the release of the active ingredient duringthe cultivation period, in particular, those effectively applied tohardly water-soluble active ingredients. It is another object of thepresent invention to provide a method for producing the same and amethod for using the same.

DISCLOSURE OF THE INVENTION

The inventors have conducted extensive studies in order to accomplishthe foregoing objects, and have found out that the desired objects canbe achieved by a coated granular pesticide which comprises a granularpesticide comprising a hardly water-soluble active ingredient and awater-swelling substance, whose surface is coated with a film mainlycomprising a thermoplastic resin. On the basis of this finding, thepresent invention has been completed.

As the thermoplastic resin of the coating film, it is preferred to useat least one polymer selected from the group consisting of olefinicpolymers and olefinic copolymers comprising an olefin as a majormonomer.

The coating film preferably comprises not more than 15% by weight of anethylene/vinyl acetate copolymer. It is also preferred that the coatingfilm comprises a surfactant, an powdery inorganic substance insoluble orhardly soluble in water, a water-absorbing and/or water-soluble finepolymer powder, a thermosetting resin or a biodegradable polymerinsoluble or hardly soluble in water, which may be used alone or in anycombination.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-A and 1-B are photographs of the coated granular pesticideaccording to the present invention before and after the breakage of thecoating film, respectively;

FIG. 2 is a schematic diagram illustrating an embodiment of a preferredapparatus which can be used in the production of the coated granularpesticide according to the present invention;

FIGS. 3-A to 3-C are photographs for ilustrating the breakage of thecoating film of the coated granular pesticide 2 with time, respectively;

FIG. 4 is a graph showing the cumulative release percentage of thecoated granular pesticides 34 to 40 over a desired period of time;

FIG. 5 is a graph showing the differential release percentage of thecoated granular pesticide mixtures 1 to 3 over a desired period of time;

FIG. 6 is a graph showing changes, with time, in the release percentagesof coated granular pesticides 41 and 42 over a desired period of time;

FIG. 7 is a graph showing the change, with time, in the cocenntration ofthe active ingredient of the coated granular pesticide 55(early-release-initiating type coated granular herbicide) in water; and

FIG. 8 is a graph showing changes, with time, in the concentration ofthe active ngredients of the coated granular pesticide mixtures 11 to 16in water.

1 spouting column;

2 opening for introducing granules;

3 outlet for exhaust gas;

4 spray nozzle;

5 granular pesticide;

6 pump;

7 opening for withdrawal;

8 heat exchanger;

9 orifice flowmeter;

10 blower;

11 dissolution tank;

12 mixed solution of film-forming materials;

T₁ temperature of flowing gas;

T₂ temperature of granular pesticide;

T₃ temperature of exhaust gas;

SL steam

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will hereinafter be described in more detail.

The coated granular pesticide according to the present invention is atimed-release, sustained release type coated granular pesticide whichdoes not release externally the hardly water-soluble active ingredientincluded in the granular pesticide within a predetermined period of timetill the coating film is disintegrated, but the active ingredient isgradually and externally released after once the disintegration of thefilm is initiated.

More specifically, in the coated granular pesticide according to thepresent invention, water present in the external environment penetratesinto the inside of the coated granular pesticide through the coatingfilm, where the water-swelling substance gradually absorbs the water toswell and grow its volume, thereby applying increasing stress to thecoating film. When the stress due to the swelling exceeds the thresholdstress of the coating film, cracks are formed on the film, through whichwater rapidly enters into the coated pesticide to accelerate theswelling of the water-swelling substance and thus to grow the cracksthereby rapidly disintegrating the coating film. Consequently, thehardly water-soluble active ingredient included in the granularpesticide comes in close contact with a large amount of water and as aresult, the release of the hardly water-soluble active ingredient isinitiated.

Photographs illustrating the breakage of the film of the coated granularpesticide according to the present invention are shown in FIG. 1. Morespecifically, FIG. 1-A and FIG. 1-B are photographs showing the coatedgranular pesticide 1 prior to and after the breakage of the coatingfilm.

The present invention makes it possible to control the time required forthe disintegration of the film and the initiation of the release of thehardly water-soluble active ingredient after the application of thecoated granular pesticide (hereinafter referred to as"film-disintegration time"). To this end, it is important to take intoconsideration the moisture permeability of the film, the criticalstrength of the film and the swelling ability of the granular pesticide.

The moisture permeability of the film is greatly affected by thefilm-forming components, namely the thermoplastic resin used as aprincipal ingredient for the film and other components optionallyincorporated such as surfactants, powdery inorganic substances,water-absorbing polymer fine particles, water-soluble polymer fineparticles, thermosetting resins and/or hardly water-soluble orwater-insoluble biodegradable polymers. The critical strength of thefilm is substantially dependent upon the film-forming components and thethickness of the film, for example, the kinds of thermoplastic resinsused, the thickness and the uniformity of the film. The swellingproperties of the granular pesticide vary depending on the kinds of thewater-swelling substances as an ingredient of the granular pesticide.

According to the present invention, the film-disintegration time asdefined above can be elongated by combining a thick and uniform filmhaving high critical strength and poor moisture permeability with awater-swelling substance having poor swelling properties. On the otherhand, the film-disintegration time can be reduced by combining a thinand uneven film having low critical strength and excellent moisturepermeability with a water-swelling substance having good swellingproperties.

In particular, the film-disintegration time is susceptible to themoisture permeability of the film and therefore, special attentionshould be paid to the control of the moisture permeability of the film.

If the moisture permeability of the film is extremely high, thewater-swelling substance may rapidly swell and the film may bedisintegrated almost at the same time when the coated granular pesticideis applied to a water-rich area such as a paddy field.

According to the present invention, various coated granular pesticidesadapted for crops to which they are pplied and cultivating conditions ofthe crops can be obtained by appropriately controlling the moistureerasability and critical strength of such a film and the water-swellingproperties of the granular pesticide.

The coated granular pesticide according to the present inventioncomprises, as an active ingredient, a hardly water-soluble activeingredient having an insecticidal, fungicidal or herbicidal effect or aplant growth regulating effect. In addition, the hardly water-solubleactive ingredient may be a single ingredient or a combination of aplurality of ingredients and the kinds of the ingredients andcombinations thereof are not particularly restricted to specific ones.

The term "hardly water-soluble active ingredient" herein used meansthose having a solubility in water of not more than 1000 ppm (at 20°C.). In the present invention, preferably used are hardly water-solubleactive ingredients having a solubility in water of not more than 1000ppm (at 25° C.), in particular, not more than 600 ppm and morepreferably not more than 50 ppm.

In this respect, if using an active ingredient having a highersolubility in water, a large amount of the active ingredient is releasedat the initial stage when the coated granular pesticide initiates therelease of the active ingredient, and thus the chemical injury of cropscan be caused and the sustained release effect of the pesticide cannotbe attained.

Specific examples of the hardly water-soluble active ingredients usableherein are1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidine-2-ylideneamine,5-methyl-1,2,4-triazolo(3,4-b)benzothiazole,3-allyloxy-1,2-benzoisothiazole-1,1-dioxide,2-chloro-4-ethylamino-6-isopropylamino-s-triazine,1-(2-chloroimidazo[1,2-a]pyridin-3-ylsulfonyl)-3-(4,6-dimethoxypyrimidin-2-ylurea,2-chloro-4,6-bis(ethylamino)-s-triazine,2-benzothiazol-2-yloxy-N-methylacetoanilide,methyl=-α-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-o-toluate,S-(4-chlorobenzyl)-N,N-diethylthiocarbamate,S-benzyl=1,2-dimethylpropyl(ethyl)thiocarbamate,2,4-dichlorophenyl-3'-methoxy-4'-nitrophenyl ether,2-methylthio-4-ethylamino-6-(1,2-dimethylpropylamino)-s-triazine,4-(2,4-dichlorobenzoyl)-1,3-dimethyl-5-pyrazolyl-p-toluenesulfonate,2-methylthio-4,6-bis(ethylamino)-s-triazine,S-1-methyl-1-phenylethyl=piperidine-1-carbothioate, 1-(α,α-dimethylbenzyl)-3-(p-tolyl) urea,2-chloro-N-(3-methoxy-2-tenyl)-2',6'-dimethylacetoanilide,2-chloro-2',6'-diethyl-N-(butoxymethyl)acetoanilide, ethyl2,4-dichlorophenoxy acetate, ethyl 2-methyl-4-chlorophenoxy acetate,(E)-(S)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pent-1-en-3-ol,(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-oland 4'-chloro-2'-(α-hydroxybenzyl)isonicotinanilide.

The water-swelling substance used in the coated granular pesticideaccording to the present invention is a substance capable of undergoinga volume-expansion through absorption of water and examples thereofinclude bentonites, starches and highly water-absorbing polymers.

As has been well-known in the art, the water-swelling properties ofbentonite vary depending on the composition and particle size thereof.Any particular problem does not arise even when using, for example,calcium type bentonite which is rich in calcium ions and magnesium ionsand has a low swelling ability and activated type bentonite which istreated with soda to artificially impart the swelling activity, butpreferred are sodium type bentonite which has a high swelling ability,i.e., which is capable of absorbing a large amount of water.

Examples of starches are naturally occurring starches such as cornstarch and potato starch; and a variety of processed starch productssuch as oxidized starches, methylated starches and carboxymethylatedstarches.

Examples of highly water-absorbable polymers include highlywater-absorbable cellulosic polymers, highly water-absorbable polyvinylalcoholic polymers and highly water-absorbable acrylic polymers.

These water swelling substances may be used alone or in any combinationand the kinds and combinations thereof are not restricted to specificones.

In the present invention, the foregoing hardly water-soluble activeingredient and the foregoing substance having a water-swelling abilityare mixed together to give a granular pesticide. The granular pesticidepreferably has a particle size ranging from 0.5 to 10 mm and morepreferably 1 to 5 mm. Such a granular pesticide is obtained throughgranulation according to the currently used method, but may easily beproduced using granulation through extrusion. Moreover, in this respect,the foregoing granular pesticide can easily be produced if an auxiliaryagent for granulation and/or a binder are used during the granulation.

Examples of auxiliary agents for granulation include powdery inorganicsubstances such as clay, kaolin and vermiculite powder; powdery organicsubstances such as powdered rice husk; and fertilizers such as urea,ammonium sulfate and ammonium chloride.

Examples of binders are gum arabic, carboxymethyl cellulose,hydroxyethyl cellulose and polyvinyl alcohol.

In the present invention, the foregoing granular pesticide is coveredwith a film mainly comprising a thermoplastic resin.

The thermoplastic resin used as a principal component for the film ispreferably resins having low water permeability and specific examplesthereof include olefinic polymers such as polypropylene, polyethylene,polybutene and polystyrene; olefinic copolymers mainly comprisingolefins such as ethylene/propylene copolymer, ethylene/carbon monoxidecopolymer, butene/ethylene copolymer, butene/propylene copolymer,ethylene/vinyl acetate copolymer, ethylene/vinyl acetate/carbon monoxidecopolymer, ethylene/acrylic acid copolymer and ethylene/methacrylatecopolymer; vinylidene chloride type copolymers such as vinylidenechloride/vinyl chloride copolymer; diene type polymers such as butadienepolymer, isoprene polymer, chloroprene polymer, butadiene/styrenecopolymer, EPDM polymer and styrene/isoprene copolymer; and waxes suchas bees wax, haze wax and paraffins. Among these thermoplastic resins,preferred are olefinic polymers and olefinic copolymers mainlycomprising olefins.

These thermoplastic resins may be used alone or in any combination of atleast two of them. In addition, they may optionally be used incombination with natural resins such as naturally occurring gums androsins; fats and oils; and/or modified fats and oils. The kinds andcombinations thereof are not restricted to any specific one.

Thermoplastic resins each having a high elastic modulus such asethylene/vinyl acetate copolymer, ethylene/vinyl acetate/carbon monoxidecopolymer and diene type polymers may serve to control thefilm-disintegration time since the resins can impart flexibility to thefilm and has an effect of relieving the internal stress due to theswelling of the granular pesticide, but if these polymers are present inthe film in a large amount, the film-disintegration time may extremelybe prolonged and the resulting film may not form cracks. Therefore, theamount of the polymer to be incorporated into the film is preferablyless than 20% by weight and more preferably not more than 15% by weight.

In the present invention, a surfactant may be added to the film tocontrol the moisture permeability of the film and to thus control thedisintegration time of the resulting film of the coated granularpesticide. The surfactant permits the improvement of the moisturepermeability of the film and accordingly, shows an effect of reducingthe film-disintegration time. The moisture permeability of the resultingfilm is sometimes reduced to a level practically acceptable depending onthe kinds of the thermoplastic resins used for forming the film andcracks may be formed with difficulty. The use of a surfactant is quiteeffective in such cases.

The surfactants usable herein suitably have an HLB value ranging from 6to 20, preferably 9 to 16 and more preferably 11 to 13. In this regard,the hydrophilicity of the surfactant is increasingly strong as the HLBvalue thereof exceeds 20. For this reason, such a surfactant cannotuniformly be dispersed in the resulting film and this may become a causeof defects of the film. On the other hand, if the surfactant used ishighly lipophilic and has an HLB value of less than 6, it may sometimesbe impossible to achieve an intended effect of increasing the moisturepermeability of the film to thus reduce the film-disintegration time.

The surfactant usable herein may be anionic, cationic, nonionic andamphoteric surfactants, which may be used alone or as a mixture of aplurality of these surfactants while adjusting the HLB value to thelevel falling within the range defined above. In the present invention,particularly preferred are nonionic surfactants.

Examples of anionic surfactants are higher fatty acid salts, higheralkyl dicarboxylic acid salts, sulfuric acid ester salts of higheralcohols, higher alkyl-sulfonic acid salts, higher alkyl-disulfonic acidsalts, sulfonated higher fatty acid salts and higher alkyl phosphoricacid ester salts; examples of cationic surfactants are higheralkyl-amine salts and quaternary ammonium salts; and examples ofnonionic surfactants are fatty acid esters of polyols and polyethyleneoxide condensates. In addition, examples of amphoteric surfactants arebetaine type, glycine type, alanine type and sulfobetaine type ones.

Among these surfactants, preferred are, for instance, polyoxyethylenealkyl allyl ethers, polyoxyethylene alkyl ethers and polyoxyethylenealkyl phenyl ethers.

The amount of the surfactants to be added to the film preferably rangesfrom 0.01 to 20% by weight and more preferably 0.05 to 10% by weight, onthe basis of the total weight of the film. This is because if the amountthereof is less than 0.01% by weight, it is difficult to achieve theintended effect of the surfactant used, while the use thereof in anamount of more than 20% by weight is unfavorable from the economicalstandpoint.

The molecular weight of the surfactant preferably ranges from 100 to1000.

Moreover, the film used in the present invention may further comprise apowdery inorganic substance for the purpose of adjusting thefilm-disintegration time of the resulting coated granular pesticide.Powdery inorganic substances show an effect of reducing thefilm-disintegration time. The powdery inorganic substances usable hereinare preferably those insoluble or hardly soluble in water. Specificexamples thereof are talc, clay, metal oxides, silicate mineral powder,glass, carbonates or sulfates of alkaline earth metals and sulfur.

These powdery inorganic substances must completely be embedded in theresulting film and accordingly, those having a particle size smallerthan the thickness of the film. For instance, the particle size thereofis preferably not more than 50 μm and more preferably 1 to 20 μn. Theamount of the inorganic powder to be added to the film is preferably notless than 50% by weight on the basis of the total weight of the film,but it is not particularly restricted to this specific range.

The coated granular pesticide may comprise, in the film, fine particlesof a water-absorbing polymer and/or a water-soluble polymer in order toadjust the film-disintegration time of the pesticide. These fineparticles of water-absorbing and/or water-soluble polymers show aneffect of reducing the film-disintegration time of the film.

Examples of fine particles of water-absorbing and/or water-solublepolymers are fine particles of polyvinyl alcohol, polyvinylpyrrolidone,methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose,sodium carboxymethyl cellulose, hydroxypropylmethyl cellulose, calciumcarboxymethyl cellulose, carboxymethylethyl cellulose, dextrin,alginates, gelatin, pectin, pullulan, polyacrylic acid, sodiumpolyphosphate, isobutylene copolymers and polyethylene oxide.

The particle size of these fine particles ranges from 0.1 to 100 μm andpreferably 0.5 to 50 μm. If the particle size is greater than 100 μm,they cannot easily be dispersed in the film. On the other hand, it isdifficult to prepare a synthetic polymer having a particle size of lessthan 0.1 μm, and such a polymer cannot show its characteristicproperties.

The amount of these fine particles to be added to the film preferablyranges from 0.1 to 30% by weight on the basis of the total weight of thefilm.

The coated granular pesticide of the present invention may furthercomprise, in the coating film, a thermosetting resin for the purpose ofcontrolling the film-disintegration time of the coated granule. Such athermosetting resin shows an effect of reducing the film-disintegrationtime of the resulting film.

Examples of such thermosetting resins are those obtained throughreactions of acid anhydrides with amines and/or diamines such aspolyamide, polyimide, bismaleimide, polyamideimide, polyetherimide,maleimide and polyetheramide.

These thermosetting resins used herein may be in any form such as asolution, powder or an intermediate thereof. For instance, thethermosetting resin in a powdery state which can be used in theinvention may be prepared by heat conditions of the soil in addition tothe hydrolysis by the foregoing hydrolases.

In case of the coated granular pesticide whose coating film comprisessuch a biodegradable polymer hardly soluble or insoluble in water, thecleavage of the backbone chain of the biodegradable polymer is graduallyproceeds immediately after the application thereof to fields todecompose and deteriorate the film, the strength of the film is reducedduring the process, and the water in the fields rapidly penetrates intothe coated granule through the film after the lapse of a predeterminedperiod of time, resulting in the release of the active ingredient of thecoated granule. Moreover, the biodegradable polymer likewise serves toeasily break the coating film made of the thermoplastic resin remainingafter the complete release of the active ingredient into pieces to thusimprove the decomposition speed of the film, i.e., the rate offilm-decomposition or disappearance.

In the present invention, the biodegradable polymer hardly soluble orinsoluble in water is not restricted to specific ones inasmuch as theycan gradually be decomposed under natural environmental conditions, butis preferably an ester of a hydroxycarboxylic acid such as an aliphaticpolyester represented by the following general formula (I):

    H--(O--R.sub.1 --O--CO--R.sub.2 --CO).sub.n --O--R.sub.1 --OH(I)

treating a polyamino acid solution obtained by reacting an acidanhydride with an amine and/or a diamine at a temperature ranging from100 to 200° C., preferably 110 to 160° C. to remove the solvent and thenpulverizing the solid product in a ball mill or a mixer. The heattreatment may be carried out at a lower temperature so far as thesolvent can be removed, but most of solvents in which thermosettingresins are soluble are in general polar ones and frequently have a highboiling point of not less than 100° C.

The thermosetting resins in a powdery state preferably have a particlesize ranging from 0.1 to 100 μm and the amount thereof to be added tothe film preferably ranges from 0.1 to 30% by weight on the basis of thetotal weight of the film.

The particulate coated pesticide according to the present invention maycomprise, in the coating film, a biodegradable polymer hardly soluble orinsoluble in water in order to control the film-disintegration time ofthe film. The biodegradable polymer hardly soluble or insoluble in watershows an effect of reducing the film-disintegration time of theresulting film.

The backbone chain of the biodegradable polymer hardly soluble orinsoluble in water used in the present invention is cleaved by theaction of metabolites of microorganisms in soil, in particular,hydrolases or other hydrolases, for example, introduced into soil fromair or water or artificially mixed with soil. The biodegradable polymermay further be hydrolyzed under the usual environmental (wherein R₁ andR₂ each independently represents an alkylene group having 2 to 10 carbonatoms and n is a numerical value ranging from 10 to 2000).

Specific examples of the polymeric hydroxycarboxylic acids representedby formula (I) are polylactones such as poly-ε-caprolactone,poly-δ-valerolactone, poly-β-propiolactone, poly-γ-butyrolactone,polylactic acid and polyglycolic acid; polyhydroxy alkanoates such aspoly-3-hydroxybutyric acid and poly-3-hydroxyvaleric acid; polyacidanhydrides, polyorthoesters, urethane bond-containing aliphaticpolyesters and copolymers thereof. These biodegradable polymer hardlysoluble or insoluble in water may be combined with any thermoplasticsubstance. The molecular weight of such a thermoplastic substancepreferably ranges from about 2000 to about 300,000. The polylactic acidmonomer may be present in any kinds of three optical isomers, i.e., L-,D- and D, L-isomers, and all of these isomers may ensure the intendedpurpose of the present invention.

The amount of the biodegradable polymer hardly soluble or insoluble inwater to be added to the coating film preferably in the range of from0.1 to 30% by weight on the basis of the total weight of the film.

The coated granular pesticide according to the present invention may beproduced by spraying a granular pesticide which is in the fluidizedstate by the action of a hot gas flow with a mixed solution obtained bydissolving film-forming materials in a solvent while drying and removingthe solvent sprayed on the pesticide to thus form a film on the surfaceof the granular pesticide.

An example of a preferred coating device usable in the method forproducing the coated granular pesticide according to the presentinvention is shown in FIG. 2.

In FIG. 2, a granular pesticide (5) is fed to a spouting column (1)through an opening (2) for introducing granular pesticides disposed onthe side of the column. A fluid gas, preferably air which is introducedinto the device by a blower (10), passes through an orifice flowmeter(9) and is heated in a heat exchanger (8), upwardly passes through thespouting column (1) and is discharged through an outlet for exhaust gas(3) disposed on the upper portion of the spouting column (1). Theheating of the fluid gas can be carried out using, for instance, steam(SL). The hot fluid gas having a temperature of T₁ heats the granularpesticide (5) up to a temperature of T₂, while maintaining the fluidizedstate of the granular pesticide. On the other hand, a thermoplasticresin as a film-forming material is dissolved in an organic solvent in adissolution tank (11) while applying heat thereto using, for instance,steam (SL) and optionally other additives are dissolved or mixed withthe solution. The resulting mixed solution (12) of the film-formingmaterials is sprayed on the granular pesticide (5) flowing through thespouting column (1), through a pump (6) and a spray nozzle (4), thus themixed solution (12) of the film-forming materials is adhered to thesurface of the granular pesticide simultaneous with or in parallel withthe evaporation of the solvent present in the mixed solution (12)through heating to thus form a film on the granular pesticide (5). Thesolvent thus evaporated is discharged through the outlet for exhaust gas(3) together with the fluid gas. They can be separated from one anotherand can be recovered by the usual method. The operation of this devicecan be optimized by appropriately adjusting, for instance, the flow rateand the temperature T₁ of the fluid gas, the temperature T₂ of thegranular pesticide (5) and the temperature T₃ of the exhaust gasdepending on the characteristic properties (for instance, particle size)of the granular pesticide (5), the composition of the mixed solution(12) of the film-forming materials or the like. The completed granularpesticide is removed from the device through an opening (7) forwithdrawal fitted to the lower end of the spouting column (1).

In the present invention, it is possible to use a mixture of at leasttwo coated granular pesticides which have a differentrelease-suppression term of the active ingredient from one another. Sucha mixture is particularly useful since the release-suppression term andthe released amount of the active ingredient having insecticidal,fungicidal or herbicidal effect required for the cultivation andmanagement of field crops and garden crops can be controlled or adjustedby a single application thereof.

When using an active ingredient having insecticidal and/or fungicidaleffects as the hardly water-soluble active ingredient, the combinationof a plurality of coated granular pesticides having differentrelease-suppression terms is not limited to specific ones inasmuch asany specific combination permits the long-lasting release of the activeingredient having insecticidal and/or fungicidal effects required forthe cultivation and management of field crops over the entire growingperiod, but it is preferred to appropriately combine an earlyrelease-intiation type coated granular pesticide which can initiate therelease of the active ingredient after 2 to 5 weeks from the applicationthereof to fields and a late release-intiation type one which caninitiate the release of the active ingredient after 6 to 9 weeks fromthe application thereof to fields.

Such a combination of the early release-intiation type coated granularpesticide with the late release-intiation type one is suitably used forcontrolling blast of paddy rice (for controlling leaf blast which wouldbe developed after one month from the rice transplanting and head blastwhich would be developed after 2.5 months from the rice transplanting).

When using an active ingredient having a herbicidal effect as the hardlywater-soluble active ingredient, the combination of a plurality ofcoated granular pesticides having different release-suppression terms isnot limited to specific ones inasmuch as any specific combinationpermits the long-lasting release of the active ingredient having aherbicidal effect required for the cultivation and management of fieldcrops over the entire growing period, but it is preferred toappropriately combine an early release-intiation type coated granularpesticide which can initiate the release of the active ingredient after1 to 14 days from the application thereof to fields and a laterelease-intiation type one which can initiate the release of the activeingredient after 15 to 40 days from the application thereof to fields.

The coated granular pesticide of the present invention permits theinitiation of the release of the hardly water-soluble active ingredientat the time when crops require the active ingredient. Therefore, thepesticide of the present invention does not cause any chemical injury ofcrops and also permits the sustained release of the active ingredient ata low concentration which does not adversely affect the growingenvironment of the crops.

For this reason, even if the coated granular pesticide is applied tofields simultaneously with the transplantation of seedlings, thegranular pesticide initiates the release of its hardly water-solubleactive ingredient after the rooting of the transplanted seedlings andthe released hardly water-soluble active ingredient is completelyconsumed for weed-killing, pasteurization and for controlling insects.Accordingly, the transplanted seedlings are not adversely affected bythe pesticide and the production of field crops with safety ispermitted.

It is optionally possible to use a coated granular pesticide comprisinga coated water-soluble active ingredient in combination with thepesticide of the present invention, in such an extent that the initialrelease thereof does not have any adverse influence. In this case, therelease-initiation time corresponds to the time when cracks are formedon the film.

In the present invention, the coated granular pesticide and a mixturethereof may be applied to fields at any desired period, but they arepreferably applied simultaneously with or immediately before thetransplantation of seedlings since the time required for farm workingcan substantially be reduced. Particularly preferably, they are appliedto holes or furrow formed on the side of seedlings simultaneously withtransplantation of seedlings, or alternatively they are applied to asubstrate for raising seedlings immediately before the transplantationthereof and immediately thereafter, the seedlings are transplanted tofields. It is also possible to combine the coated granular pesticideaccording to the present invention or a mixture thereof with acommercially available pesticide and to apply the resulting mixture sothat the latter would be released during the controlled release term ofthe pesticide of the present invention.

The coated granular pesticide of the present invention can likewise beincorporated into a seedling-support substance having water holdingproperties (hereinafter referred to as "water-holding material") andused as a substrate for raising seedlings. Such a substrate for raisingseedlings consisting of the coated granular pesticide and thewater-holding material is suitably used in the cultivating method whichcomprises seeding rice seeds in a nursery box, raising the seedlings andthen transplanting the resulting seedlings to fields. The use of thesubstrate for raising seedlings according to the present invention caneliminate the application of any granular pesticide having aninsecticidal, fungicidal or herbicidal effect prior to transplantationof seedlings and this accordingly permits the substantial reduction inthe quantity of work during transplantation, in particular, that of alarge-scale farm household who raises seedlings using a large number ofnursery boxes. In addition, if raising seedlings by the use of thesubstrate for raising seedlings according to the present invention, theseedlings are transplanted while the coated granular pesticide is heldaround the rooting of the seedlings and therefore, this leads toimprovement in the absorption and utilization efficiency of the activeingredient released from the coated granular pesticide, substantialreduction of the active ingredient washed away into the soil andreduction of environmental loads.

The water-holding materials usable herein are not restricted to anyspecific one inasmuch as they have good water holding properties andexamples thereof are natural soil, naturally occurring organicsubstances such as wood chips, scum of pulp, peat-moss, sphagnum andcoir; foamed resins; and inorganic porous materials such as perlite andvermiculite, but preferred are vermiculite, peat-moss and coconut mealbecause they are inexpensive and stable supply thereof can be ensured.These water-holding materials may be used alone or in a blend of atleast two of them. In addition, these water-holding substances mayfurther comprise various kinds of additives for controllingphysicochemical properties such as pH and electrical conductivity (EC).

To the substrate for raising seedlings according to the presentinvention, there may, if needed, be added fertilizers. In this respect,however, if using fast-acting fertilizers, they are preferably used inamounts of about 1 to 4 g, respectively, as expressed in terms of N(nitrogen), P₂ O₃ (phosphoric acid) and K₂ O (potash) per unit nurserybox (internal size: 28 cm (length)×58 cm (width)×3 cm (depth). If thesefertilizer components each exceeds 4 g, young seedlings may suffer fromconcentration injury.

To the substrate for raising seedlings according to the presentinvention, there may be applied, in addition to fast-acting fertilizers,coated granular fertilizer whose release rate is physically controlledby coating each granular fertilizer with a film and micro elements.

Examples of such micro elements are compounds of, for instance,magnesium, calcium, iron, manganese, boron, zinc, copper and molybdenum.

Water-soluble micro elements are fast-acting fertilizers and therefore,they are effective for soil deficient in these component, but have sucha tendency that they are washed away if the amount of water used forirrigation increases. Moreover, if the added amount of the microelements is large, seedlings are damaged due to their excess and forthis reason, the use of micro elements soluble in citric acid isrecommended. Such citric acid-soluble micro elements are hardly solublein water and the elements thereof are slowly released even if they areadded to the substrate in a large amount during raising seedlings, andtherefore, the use of such micro elements are particularly preferred inorder to prevent any deficiency of these trace elements during raisingseedlings.

Examples of the foregoing coated granular fertilizers are thosedisclosed in JP-A 56567/1994 or JP-A 4887/1993 in which an oil modifiedalkyd resins is used as a coating film; and those disclosed in JP-A147888/1988 wherein a polyolefinic resin is used as such a coating filmand specific examples thereof usable herein include coated granularfertilizers commercially available under the trade names of Long (AsahiChemical Industry Co., Ltd.), LP Coat (Chisso Corporation), Celacoat(Central Glass Co., Ltd.) and M Coat (Mitsubishi Chemical Co.). If thesefertilizers are used for raising seedlings, roots of seedlings areformed around the granular fertilizer and thus the fertilizer-absorptionand -utilization efficiencies are markedly improved.

The coated granular fertilizer preferably has a release rate during theseedling-raising term ranging from 0.5 to 10% and more preferably 1 to7%. Fertilizers having a release rate beyond the range defined above mayalso be used, but if the release rate exceeds 10%, seedlings may sufferfrom concentration injury due to the fertilizer component, while if itis less than 0.5%, the seedlings may insufficiently grow. Moreover, itis necessary to adjust the amount of the fertilizer to be applieddepending on the term for raising seedlings to be transplanted.

These coated granular fertilizers may be mixed with the water-holdingmaterials in such an amount that does not impair the functions of thewater-holding materials (water-holding and seedling-supportingfunctions). More specifically, if the amount of the coated granularfertilizer is excessively large, the water-holding properties of theresulting substrate are impaired, while if it is extremely small,sufficient fertilization during raising seedling cannot be ensured.Accordingly, it is preferable to admix 5 to 50 parts by weight of thecoated granular fertilizer with 50 to 95 parts by weight of thewater-holding material. These numerical values defined above correspondto cases where the water-holding material is assumed to be a mineralsubstance such as natural soil. In case of, for instance, water-holdingmaterials having a smaller specific gravity such as vermiculite andpeat-moss, however, the amount thereof to be used may be less than 50parts by weight so far as the resulting mixture exhibits functions ofwater-holding materials. Therefore, the foregoing range is simply astandard for judgment.

The amount of the coated granular pesticide to be used varies dependingon the content of the active ingredient thereof, but it is in generalsufficient to use the same in a small amount and thus the pesticide doesnot impair the functions of the water-holding material. The amount ofthe coated pesticide as a standard is preferably not more than 100 g pernursery box having the size specified above.

Moreover, the substrate for raising seedling according to the presentinvention may likewise comprise a further component such as a growthregulator, a growth promoter or the like.

The substrate for raising seedling according to the present inventionmay be prepared by any conventionally known method. For instance, it canbe prepared by admixing a water-holding material and the coated granularpesticide as well as optional components such as a fertilizer and microelements in a mixing machine. The resulting mixture (the substrate forraising seedling according to the present invention) may be used in avariety of methods. For instance, it may be used as bed soil and/or soilcover in fields or nursery boxes; or it may be mixed with seeds uponseeding. In particular, when it is used in a nursery box, it can berecommended that a layer of a mixture of seeds with the substrate forraising seedling according to the present invention, which comprises awater-holding material, the coated granular pesticide and coatedgranular fertilizers, should be arranged between a bed soil layer and asoil cover layer. This is because the active ingredient, fertilizercomponents and micro elements are present in the vicinity of seeds andtherefore, these components are absorbed through roots and used with ahigh efficiency, after rooting the seeds.

The present invention will hereinafter be described in more detail withreference to the following Production Experiments of Granular Pesticidesand Production Experiments and Examples, but the present invention isnot limited to these specific Examples. In the following Examples, theterm "%" means "% by weight" unless otherwise specified.

Production of Granular Pesicide

Granular Pesticides (G.P.) A to M

Each mixture of ingredients for granules having each correspondingcomposition shown in Table 1 was kneaded in a kneader while addingwater, followed by granulation through extrusion and forming intospherical granules using a shaping machine. Then the granulated productwas dried to thus give each granular pesticide containing a hardlywater-soluble active ingredient and having a particle size ranging from0.8 to 1.4 mm. In the foregoing preparation, the polymer used forpreparing the granular pesticide D was used after dissolving in water.

                  TABLE 1                                                         ______________________________________                                        Composition of G.P. (% by weight)                                               G.    Active                                                                  P. Ingredient Material I Material II Material III                           ______________________________________                                        A   A.M..sup.1) A                                                                          10     bentonite                                                                            50  clay 40                                          B A.M. A 5 bentonite 95                                                       C A.M. B 20 bentonite 40 starch 20 clay 20                                    D A.M. C 5 bentonite 5 kao- 85 polymer  5                                          lin                                                                      E A.M. D 2 starch 95 gel- 1 ammonium 2                                             atin  phosphate                                                          F A.M. A 15 bentonite 60 clay 25                                              G A.M. A 15 bentonite 30 clay 55                                              H A.M. E 7 bentonite 30 clay 63                                               I A.M. F 10 bentonite 30 clay 60                                              J A.M. E 7 bentonite 30 clay 53                                                A.M. F 10                                                                    K A.M. A 14.5 bentonite 30 clay 55.5                                          L A.M. C 3.5 bentonite 30 clay 66.5                                           M A.M. C 1 bentonite 30 clay 69                                             ______________________________________                                    

*: Active Incrredient:

A.I. A: 2-benzothiazol-2-yloxy-N-methylacetoanilide (content=87%)

A.I. B: 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (content=75%)

A.I. C: 1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine(content=71%)

A.I. D: 2-chloro-4,6-bis(ethylamino)-s-triazine (content=50%)

A.I. E: 5-methyl-1,2,4-triazolo(3,4-b)benzothiazole (content=75%)

A.I. F: 1,3-bis(carbamoylthio)-2-(N,N-dimethylamino)propanehydrochloride (content=50% by weight)

*: Water-Swelling Material

Bentonite: a product available from Wako Pure Chemical Industry Co.,Ltd.

Starch: corn starch available from Wako Pure Chemnical Industry Co.,Ltd.

Gelatin

*: Binder, Auxiliary Agent for Granulation or the Like

Polymer: sodium polyacrylate (degree of polymerization: 15 22,000 to70,000)

Ammonium Phosphate: diammonium phosphate

Clay

Kaolin

Synthesis of Thermosetting Resin

To a 300 ml four-necked flask, there was added 100 ml of diethyleneglycol dimethyl ether, followed by dissolution of 18.9 g of α,ω-bis(3-aminopropyl)polydimethyl siloxane, cooling the content of theflask down to a temperature of 10° C. while stirring with a stirringmachine, subsequent addition of 4.6 g of maleic anhydride and reactionof these ingredients to give a thermosetting resin A.

In the same manner, to a 300 ml four-necked flask, there was added 100ml of N,N-dimethylacetamide, followed by dissolution of 4.7 g ofp-aminobenzoic acid, cooling the content of the flask down to atemperature of 7° C. while stirring with a stirring machine, subsequentaddition of 18.9 g of benzophenone tetracarboxylic acid dianhydride andreaction of these ingredients to give a thermosetting resin B.

Production of Coated Granular Pesticide (C.G.P.)

As has been shown in FIG. 2, hot air having a high temperature waspassed through the interior of a spouting column (1) which was in ashape having a column diameter of 250 mm, a height of 2000 mm, an airjet-outlet diameter of 50 mm and an angle at the conical part of 50degrees, from its bottom to the top, i.e., upwardly passed through thecolumn. A blower (10) was used to introduce air, through an orificeflowmeter (9), into a heat exchanger (8) in which the air was heated toa desired high temperature and was then guided to the spouting column(1) and finally discharged through an outlet (3) for exhaust gas whichwas positioned at the upper portion of the spouting column (1). Thenthere was introduced 10 kg of each granular pesticide (5) listed inTables 2 to 7 (provided that 3 kg of each pesticide was introduced whenproducing coated granular pesticides 33 to 46) into the interior of thespouting column (1) through which the hot air was circulated, through anopening (2) for introducing granules positioned on the side of thespouting column (1) to thus fluidize the granular pesticide (5) in thepowdery state. In this regard, the flow rate and temperature of the hotair were appropriately controlled depending on the kinds of samples. Theflow rate of the granule (5) was controlled while monitoring the same bythe orifice flowmeter and the temperature thereof was adjusted whilemonitoring the hot air temperature (T₁), the granule temperature (T₂)and the exhaust gas temperature (T₃). The production of each coatedgranular pesticide was carried out at a flow rate as determined byflowmeter (9) of 4 m³ /min and the hot air temperature (T₁) of 100°C.±2° C. (provided that T₁ was set at 80° C.±2° C. when producing coatedgranular pesticides 33 to 40).

On the other hand, there were introduced, into a dissolution bath (11),ingredients for films listed in Tables 2 to 7 and tetrachloroethylene asa solvent (provided that toluene was used when producing coated granularpesticides 33 to 40), followed by admixing and stirring these componentsto give a 2.5% solution (12) of film-forming materials (provided that a5.0% solution of film-forming materials was used when producing coatedgranular pesticides 41 to 46, 49 and 50). In the foregoing preparation,the thermosetting resins in liquid states were used as such, while thosein powdery states were pulverized in a ball mill, then classified usinga sieve having a pore size of 75 μm and particles which could passthrough the sieve were used.

The solution (12) was fed to a spray nozzle (4), which was a full conetype hydraulic nozzle having a diameter of 0.6 mm and positioned at alower portion of the spouting column (1), by the action of a pump (6),at a flow rate of 0.3 kg/min (provided that it was set at 0.2 kg/minwhen producing coated granular pesticides 33 to 40), then injectedtoward and sprayed on the granular pesticide (5) in a fluidizedcondition.

Such a spraying operation was initiated when the temperature (T₂) of thegranular pesticide (G.P.) which was in the fluidized state reached agiven level, and the operation was continued for a given period of time,followed by drying the product for a predetermined time. After thedrying was completed, the blower (10) was stopped and the coatedgranular pesticide (5) was discharged through an opening (7) forwithdrawal positioned at the lowest portion of the spouting column (1)to thus obtain each coated granular pesticide (C.G.P.) 1 to 55 having acovering ratio listed in the following Table 2 to Table 7.

                                      TABLE 2                                     __________________________________________________________________________                                        Coating                                     Composition of Coating Material  Ratio                                      C.G.P.                                                                            Resin 1                                                                            Resin 2                                                                            Resin 3                                                                             Filler                                                                              S.A.A. G.P.                                                                             (%)                                       __________________________________________________________________________    1   PE-1                                                                             40           talc                                                                              60                                                                              Nonion                                                                            10 A  15                                          2 PE-1 20     talc 80 Nonion 5 A 15                                           3 PE-1 20     talc 80 Nonion 3 A 15                                           4 PE-1 20     talc 80 Nonion 2 A 15                                           5 PE-1 20     talc 80 Nonion 1 A 15                                           6 PE-1 20     talc 80 Nonion 0.5 A 15                                         7 PE-2 28 EVA 2   clay 70   B 20                                              8 PE-2 69 WAX 30 PCL 1     C 20                                               9 PE-2  5     talc 95   C 15                                                  10  PP-1 30 PCL 5   CaCO.sub.3 65   D 20                                      11  PP-1 20     clay 80 Nonion 0.1 E 15                                       12  WAX 70     talc 30   E 25                                               __________________________________________________________________________

*: The amount of the surfactant (S.A.A.) is expressed in terms of % byweight on the basis of the total weight of the Resin 1, Resin 2, Resin 3and Filler (which is 100% by weight).

                                      TABLE 3                                     __________________________________________________________________________    Composition of Coating Material   Coating Ratio                               C.G.P.                                                                            Resin 1                                                                            Resin 2                                                                            Filler 1                                                                            Filler 2                                                                           S.A.A.                                                                              G.P.                                                                             (%)                                         __________________________________________________________________________    13  PE-3                                                                             10     IB 1  talc                                                                             89      F  20                                            14 PE-3 20   IB 1 talc 79   F 20                                              15 PE-3 30   IB 1 talc 69   F 20                                              16 PE-3 20   MC 3 talc 77   F 20                                              17 PE-3 10 PE-4 10 MC 5 talc 75   F 20                                        18 PE-3 10 PE-4 10 HPC 3 talc 67   F 20                                       19 PE-2 20   IB 1 talc 79 Nonion 0.5 F 20                                     20 PE-2 20   MC 10   talc 70   F 20                                           21 PE-2 20   HPC 1 talc 79   F 15                                             22 PE-2 20   HPC 5 talc 75   F 15                                           __________________________________________________________________________

*: The amount of the surfactant (S.A.A.) is expressed in terms of % byweight on the basis of the total weight of the Resin 1, Resin 2, Filler1 and Filler 2 (which is 100% weight).

                                      TABLE 4                                     __________________________________________________________________________    Composition of Coating Material     Coating                                                 Thermosetting         Ratio                                       C.G.P. Resin 1 Resin 2 Resin Filler S.A.A. G.P. (%)                         __________________________________________________________________________    23  PE-3                                                                             10     Solution 1                                                                         1  talc                                                                             89      F  20                                          24 PE-3 20   Solution 1 1 talc 79   F 20                                      25 PE-3 30   Solution 1 1 talc 69   F 20                                      26 PE-3 10 PE-2 10 Solution 2 2 talc 78   F 20                                27 PE-2 10   Powder 1 5 talc 85   F 20                                        28 PE-2 20 PP-2 10 Powder 1 3 talc 77   F 20                                  29 PE-2 20   Powder 1 1 talc 69 Nonion 0.5 F 20                               30 PP-2 35   Solution 2 10   talc 55   F 20                                   31 PP-2 20   Powder 2 1 talc 79   F 15                                        32 PP-2 20   Powder 2 5 talc 75   F 15                                      __________________________________________________________________________

*: The amount of the surfactant (S.A.A.) is expressed in terms of % byweight on the basis of the total weight of the Resin 1, Resin 2,Thermosetting Resin and Filler (which is 100% by weight).

                  TABLE 5                                                         ______________________________________                                                                         Coating                                        Composition of Coating Material  Ratio                                      C.G.P.                                                                              Resin 1     Resin 2    Filler G.P. (%)                                  ______________________________________                                        33    PE-3      20    EVA    20  talc 60  G    20                               34 PE-2 18 Water-sol.  2 talc 80 G 20                                         35 Biodegrad. 1  1 PE-2 19 talc 80 G 20                                       36 Biodegrad. 1  3 PE-2 17 talc 80 G 20                                       37 Biodegrad. 1 10 PE-2 30 talc 60 G 20                                       38 Biodegrad. 2  5 PE-2 15 talc 80 G 20                                       39 Biodegrad. 3  2 PE-2 18 talc 80 G 20                                       40 Biodegrad. 4 10 PE-2 20 talc 70 G 20                                     ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        Composition of Coating Material                                                                             Coating Ratio                                   C.G.P. Resin 1  Resin 2   Filler G.P. (%)                                     ______________________________________                                        41     PE-2   20    paraffin                                                                            2   talc 80  H    20                                  42 PE-2 18 paraffin 2 talc 80 H 20                                            43 PE-2 18 paraffin 2 talc 80 I 20                                            44 PE-2 15 paraffin 5 talc 80 I 20                                            45 PE-2 18 paraffin 2 talc 80 J 20                                            46 PE-2 15 paraffin 5 talc 80 J 20                                            47 PE-2 18   talc 82 K 20                                                     48 PE-2 18   talc 82 L 20                                                     49 PE-2 15   talc 85 L 20                                                     50 PE-2 15 WAX 2 5 talc 80 M 20                                             ______________________________________                                    

                                      TABLE 7                                     __________________________________________________________________________                                       Coating                                      Composition of Coating Material  Ratio                                      C.G.P.                                                                            Resin 1                                                                            Resin 2                                                                            Filler 1                                                                           Filler 2                                                                             S.A.A.                                                                              G.P.                                                                             (%)                                        __________________________________________________________________________    51  PE-2                                                                             15     talc                                                                             85       Nonion                                                                            1 F  20                                           52 PE-2 25   talc 75   Nonion 2 F 20                                          53 PE-2 30   talc 70   Nonion 1 F 20                                          54 PE-2 10 PE-3 20 talc 67 HPC 3   F 20                                       55 PE-3 10   talc 89 Powder 1 1   F 20                                      __________________________________________________________________________

*: The amount of the surfactant (S.A.A.) is expressed in terms of % byweight on the basis of the total weight of the Resin 1, Resin 2, Filler1 and Filler 2 (which is 100% by weight).

PE-1: low density polyethylene: MI=20; d=0.922 g/cmn³

PE-2: ethylene-carbon monoxide copolymer: MI=0.75; CO=0.95% by weight

PE-3: low density polyethylene: MI=23; d=0.916 g/cm³

PE-4: low density polyethylene: MI=70; d=0.915 g/cm³

PP-1: copolymer type atactic polypropylene having an ethylene content of3%: Mw=60,000

PP-2: polypropylene: Mw=10,000; d=0.9 g/cm³

EVA: ethylene-vinyl acetate copolymer: MI=20; vinyl acetate content=30%by weight

WAX: polyethylene wax: Mn=8,000; d=0.97 g/cm³

WAX 2: polyethylene wax: Mn=2,000; d=0.92 g/cm³

paraffin: mp=68 to 70° C.

PCL: poly-ε-caprolactone: Mw=50,000

IB: isobutylene type copolymer

MC: methyl cellulose

Biodegrad. 1: 1,4-butanediol-succinic acid co-polycondensate: Mn=59,000

Biodegrad. 2: poly-L-lactic acid: Mw=60,000

Biodegrad. 3: polycaprolactone: Mw=50,000

Biodegrad. 4: 3-hydroxybutyric acid/3-hydroxyvaleric acid copolymer:Mw=150,000, 3-hydroxyvaleric acid content=20 mole %

Water-Sol.: polyethylene oxide: Mw=150,000 to 400,000

HPC: hydroxypropyl cellulose: 150 to 400 cp

Nonion: hexaoxyethylene nonyl phenyl ether: HLB=13

talc: average particle size=5 μm

CaCO₃ : calcium carbonate having an average particle size of 5 μm

clay: average particle size=5 μm

Solution 1: thermosetting resin A

Solution 2: thermosetting resin B

Powder 1: thermosetting resin A

Powder 2: thermosetting resin B

Production of Coated Granular Pesticide Mixture

The coated granular pesticides (C.G.P.) 41 to 46 (Table 6) produced inthe foregoing Production Experiments were blended in the rates specifiedbelow and each blend was uniformly stirred in a kneader to give variouscoated granular pesticide mixtures (coated granular pesticide mixtures 1to 16).

C.G.P. Mixture 1:

(C.G.P. 41: C.G.P. 42=1:1)

C.G.P. Mixture 2:

(C.G.P. 41: C.G.P. 42=2:1)

C.G.P. Mixture 3:

(C.G.P. 41: C.G.P. 42 1:2)

C.G.P. Mixture 4:

(C.G.P. 43: C.G.P. 44=1:1)

C.G.P. Mixture 5:

(C.G.P. 43: C.G.P. 44=2:1)

C.G.P. Mixture 6:

(C.G.P. 43: C.G.P. 44=1:2)

C.G.P. Mixture 7:

(C.G.P. 41: C.G.P. 43=1:1)

C.G.P. Mixture 8:

(C.G.P. 42: C.G.P. 44=1:1)

C.G.P. Mixture 9:

(C.G.P. 42: C.G.P. 45=1:1)

C.G.P. Mixture 10:

(C.G.P. 41: C.G.P. 46=1:1)

C.G.P. Mixture 11:

(C.G.P. 51: C.G.P. 53=1:1)

C.G.P. Mixture 12:

(C.G.P. 51: C.G.P. 53=7:3)

C.G.P. Mixture 13:

(C.G.P. 51: C.G.P. 53=6:4)

C.G.P. Mixture 14:

(C.G.P. 51: C.G.P. 52: C.G.P. 53=60:25:15)

C.G.P. Mixture 15:

(C.G.P. 53: C.G.P. 55=1:9)

C.G.P. Mixture 16:

(C.G.P. 53: C.G.P. 54: C.G.P. 55=15:15:70)

Release-Confirmation Test

Release-confirmation tests were carried out using coated granularpesticides 1 to 12 (Table 2) produced in the foregoing experiments forthe production of these granules. In these tests, there was determinedthe period required for the formation of cracks on the pesticides, thebreakage of the films thereof and the outward release of the granularpesticides present therein (release-suppression term), according to thefollowing manner.

To a beaker, there were added 500 ml of distilled water and 0.1 g ofeach coated granular pesticide 1 to 12, followed by the inspection ofthe coated granular pesticide for film-disintegration behavior withperiod. In addition, the distilled water in the beaker was sampled atregular intervals, the hardly water-soluble active ingredient present inthe sampled distilled water was analyzed by high performance liquidchromatography to thus determine the priod required till the release ofthe active ingredient was detected and the period thus determined wasdefined to be the release-suppression term of the granular pesticide.The temperature of the distilled water was maintained at 20° C. and thedetermination was carried out for 30 days after the addition of thegranule to distilled water. The results thus obtained are summarized inTable 8.

                  TABLE 8                                                         ______________________________________                                                           Release-Suppression                                          Sample Term (day)                                                           ______________________________________                                        Example 1     C.G.P. 1 10                                                       Example 2 C.G.P. 2 6 hrs.                                                     Example 3 C.G.P. 3 0.5                                                        Example 4 C.G.P. 4 1.0                                                        Example 5 C.G.P. 5 1.5                                                        Example 6 C.G.P. 6  5                                                         Example 7 C.G.P. 7 15                                                         Example 8 C.G.P. 8 24                                                         Example 9 C.G.P. 9 0.5                                                        Example 10 C.G.P. 10 17                                                       Example 11 C.G.P. 11 10                                                       Example 12 C.G.P. 12 20                                                     ______________________________________                                    

The disintegration process of the coated granular pesticide 2 is shownin FIG. 3. FIGS. 3A, 3B and 3C are photographs taken at 6 hours, 6 hoursand 5 minutes, and 6 hours and 10 minutes after the coated granularpesticide 2 was introduced into a beaker, respectively.

As will be seen from the photographs shown in FIGS. 3A to 3C, it takes aconstant time period till cracks are formed on the film of this coatedgranular pesticide and any hardly water-soluble active ingredient is notreleased at all before the formation of the cracks, but if once suchcracks are formed, the disintegration of the film proceeds acceleratedlyand the granular pesticide present therein is rapidly released.

Moreover, the results observed for the coated granular pesticides 2 to 6which differ from one another in the added amount of the surfactantindicate that the larger the amount of the surfactant added, the shorterthe release-suppression term and that the addition of a surfactant iseffective for the control of the release-suppression term.

Test 1 for Release in Water

Tests for release in water were carried out using the coated granularpesticides 13 to 32 (Tables 3 and 4) produced in the foregoingProduction Experiments. To a beaker, there were added 1000 ml ofdistilled water and 0.1 g of each coated granular pesticide (C.G.P.),followed by the inspection of the coated granular pesticide forfilm-disintegration behavior with term. In addition, the distilled waterin the beaker was sampled at regular intervals, the hardly water-solubleactive ingredient present in the sampled distilled water was analyzed byhigh performance liquid chromatography. The temperature of the distilledwater was maintained at 25° C. during the test and the determination wascarried out for 28 days after the addition of the granule to distilledwater. The results thus obtained are summarized in Tables 9 and 10. InComparative Example 1, the foregoing granular pesticide F free ofcoating film was used.

                  TABLE 9                                                         ______________________________________                                                   Concn. of Active Ingredient                                          in Water (ppm)                                                                           day     day     day   day   day                                    Sample 1 3 7 14 28                                                          ______________________________________                                        Ex. 13 C.G.P. 13 0.0     0.3   0.8   1.2   1.6                                  Ex. 14 C.G.P. 14 0.0 0.0 0.3 0.8 1.5                                          Ex. 15 C.G.P. 15 0.0 0.0 0.0 0.1 1.0                                          Ex. 16 C.G.P. 16 0.0 0.0 0.0 0.6 1.3                                          Ex. 17 C.G.P. 17 0.0 0.0 0.0 0.8 1.8                                          Ex. 18 C.G.P. 18 0.0 0.0 0.0 0.0 0.7                                          Ex. 19 C.G.P. 19 0.0 1.0 1.6 2.0 2.5                                          Ex. 20 C.G.P. 20 0.0 0.0 0.4 1.0 2.0                                          Ex. 21 C.G.P. 21 0.0 0.0 0.0 0.7 1.4                                          Ex. 22 C.G.P. 22 0.0 0.0 0.1 0.9 1.8                                          Comp. G.P. F 0.8 1.2 2.5 2.9 3.0                                              Ex. 1                                                                       ______________________________________                                    

The results listed in Table 9 indicate that the granules of ComparativeExample 1 initiates the release of the active ingredient immediatelyafter the introduction thereof into water, whereas for C.G.P. Nos. 13 to22 according to the present invention, which comprise water-absorbingpolymer fine particles and/or water-soluble polymer fine particles, anyactive ingredient is not detected, on day 1 after the introduction,clearly showing that the release of the active ingredient is initiallyinhibited and the active ingredient certainly undergoes sustainedrelease in the samples of the present invention.

Moreover, the results observed for C.G.P. Nos. 13 to which differ fromone another in the amount of Resin 1 included in the water-absorbingpolymer fine particles and/or the water-soluble polymer fine particleswith respect to the isobutylene type copolymer (Table 3) also indicatethat the larger the amount of Resin 1, the later the release-suppressionterm of the active ingredient and that the control of the amount ofResin 1 would be effective for the adjustment of the release-suppressionterm.

                  TABLE 10                                                        ______________________________________                                                   Concn. of Active Ingredient                                          in Water (ppm)                                                                           day     day     day   day   day                                    Sample 1 3 7 14 28                                                          ______________________________________                                        Ex. 23 C.G.P. 23 0.0     0.1   0.6   1.3   1.7                                  Ex. 24 C.G.P. 24 0.0 0.0 0.4 0.9 1.4                                          Ex. 25 C.G.P. 25 0.0 0.0 0.0 0.0 1.1                                          Ex. 26 C.G.P. 26 0.0 0.0 0.0 0.5 1.2                                          Ex. 27 C.G.P. 27 0.0 0.2 0.4 0.8 1.9                                          Ex. 28 C.G.P. 28 0.0 0.0 0.2 0.5 1.4                                          Ex. 29 C.G.P. 29 0.0 0.0 0.8 1.5 2.3                                          Ex. 30 C.G.P. 30 0.0 0.4 0.7 1.0 2.0                                          Ex. 31 C.G.P. 31 0.0 0.0 0.3 0.8 1.5                                          Ex. 32 C.G.P. 32 0.0 0.5 1.0 1.5 1.8                                          Comp. G.P. F 0.8 1.2 2.5 2.9 3.0                                              Ex. 1                                                                       ______________________________________                                    

The results listed in Table 10 indicate that the granules of ComparativeExample 1 initiates the release of the active ingredient immediatelyafter the introduction thereof into water, whereas for C.G.P. Nos. 23 to32 according to the present invention, which comprise thermosettingresins, any active ingredient is not detected, on day 1 after theintroduction, clearly showing that the release of the active ingredientis initially inhibited and the active ingredient certainly undergoescontrolled release in the samples of the present invention.

Moreover, the results observed for C.G.P. Nos. 23 to 25 which differfrom one another in the amount of Resin 1 with respect to thethermosetting resin (Table 4) also indicate that the larger the amountof Resin 1, the later the release-initiation time of the activeingredient and that the control of the amount of Resin 1 would beeffective for the adjustment of the release-suppression term.

Test for Examining Decomposition and Deterioration of Film

There was introduced, into a polypropylene nonwoven fabric having a sizeof 3 cm×10 cm, 10 g of each coated granular pesticide (C.G.P.) 33 to 40(Table 5) produced in the foregoing Production Experiments. The soil inthe field within a glasshouse (Tobata-Ku, Kitakyushu-Shi, Fukuoka-Ken,Japan) was digged out to a depth of 3 cm and the polypropylene nonwovenfabric was placed in the digged portion, followed by returning the soildigged out above to heap up the earth. The temperature in the glasshousewas appropriately controlled and the maximum temperature and the minimumtemperature were found to be 30 and 20° C., respectively. An appropriateamount of water was supplied to the ground by sprinkling water over theground at 8:30 and 12:30 every day using an automatic water sprinkler.These samples of the granules were taken out from the soil every twomonths to examine the granules for their conditions. After one year, thegranules were taken out, washed with water and examined for theconditions of the films thereof. The results thus obtained are listed inthe following Table 11.

                  TABLE 11                                                        ______________________________________                                                        Results Observed in                                             Sample Film-Decomposition Test                                              ______________________________________                                        Ex. 33   C.G.P. 33  Any change in shape was not                                   observed even after one year.                                               Ex. 34 C.G.P. 34 The film was disintegrated after                               two months, but there was observed                                            film residues.                                                              Ex. 35 C.G.P. 35 The film was disintegrated after                               two months, and crumbled into decay                                           upon water-washing after one year.                                          Ex. 36 C.G.P. 36 The film was disintegrated after                               two months, and crumbled into decay                                           after 8 months.                                                             Ex. 37 C.G.P. 37 The film was disintegrated after                               two months, and crumbled into decay                                           upon water-washing after one year.                                          Ex. 38 C.G.P. 38 The film was disintegrated after                               two months, and crumbled into decay                                           after 6 months.                                                             Ex. 39 C.G.P. 39 The film was disintegrated after                               two months, and crumbled into decay                                           upon water-washing after one year.                                          Ex. 40 C.G.P. 40 The film was disintegrated after                               two months, and crumbled into decay                                           atter 4 months.                                                           ______________________________________                                    

As seen from the results listed in Table 11, it was confirmed that forthe coated granular pesticide (C.G.P.) Nos. 35 to 40 which comprisedbiodegradable polymers hardly soluble or insoluble in water, the filmscrumbled into decay after one year and disappeared. In respect of C.G.P.Nos. 33 to 34, it was confirmed that C.G.P. No. 34 showed disintegrationof the film, but the decomposition of film residues was not affected somuch. The effect of decomposing the film would be ascribed to theaddition of biodegradable polymers thereto and thus the reduction in thefilm strength would contribute to the disappearance of the film.

Test 2 for Release in Water

The coated granular pesticides (C.G.P.) Nos. 34 to 40 (Table 5) producedin the foregoing production experiments were subjected to tests forexamining the release of the active ingredients in water. To a test tube(12 mm×72 mm) equipped with a cap, there was added 1.5 ml of water andeach granular pesticide was introduced into the test tube in a rate ofone granule per tube and thereafter the test tubes were capped. Using100 test tubes (or granules) per each test division, they were allowedto stand under a predetermined condition, i.e., at a water temperatureof 25° C. and the number of the granules for pesticide thusdisintegrated was counted. The test tubes were observed every day forone week after the initiation of the test and thereafter the observationwas carried out once a week. The results thus obtained are shown in FIG.4. The cumulative release rate means the number of granules tested whichare disintegrated.

The data shown in FIG. 4 indicate that all of the coated granularpesticides 34 to 40 exhibit almost identical release characteristics.

Test 3 for Release in Water

The coated granular pesticides (C.G.P.) Nos. 41 to 46 (Table 6) producedin the foregoing Production Experiments were subjected to tests forexamining the release of the active ingredients in water. Afterimmersing C.G.P. Nos. 41 to 46 in water maintained at 25° C., the numberof days required for the 10% release of the granular pesticide (G.P.)was determined and it was defined to be release-supression term. Using100 granules per test, the amount of the released G.P. was observed oncea week to thus determine the number of G.P. granules disintegrated. Theresults obtained are summarized in the following Table 12.

                  TABLE 12                                                        ______________________________________                                                           Release-Supression                                           Sample Term (Day)                                                           ______________________________________                                        Example 41    C.G.P. 41                                                                              56                                                       Example 42 C.G.P. 42 28                                                       Example 43 C.G.P. 43 56                                                       Example 44 C.G.P. 44 28                                                       Example 45 C.G.P. 45 56                                                       Example 46 C.G.P. 46 28                                                     ______________________________________                                    

The coated granular pesticide (C.G.P.) mixture Nos. 1 to 3 produced inthe foregoing Production Experiments were immersed in water maintainedat 25° C., then the release rate of the active ingredient released fromeach C.G.P. was determined every 7 days to thus give an differentialrelease rate. The differential release rate as days after application isshown in FIG. 5 as a bar graph. In addition, C.G.P. Nos. 41 and 42, eachof which is a single substance, were also examined for the accumulatedrelease rates. The resulting differential release rate as days afterapplication is shown in FIG. 6 in the form of a bar graph.

As has been shown in FIG. 6, each of C.G.P. Nos. 41 and 42, as singlesubstances, has a peak of the release rate at a relatively early stageand accordingly they undergo rapid release of the active ingredients,but the duration of the release is short. On the other hand, as shown inFIG. 5, C.G.P. mixture Nos. 2 and 3 have peaks of the release rateslower than those observed for the C.G.P. Nos. 41 and 42 as singlesubstances, but the mixtures each maintains a relatively high releaserate over a long period of time, before and behind the peak. Moreover,it is found that C.G.P. mixture No. 1 does not have any particular peak,but maintains a relatively high release rate over a very long period oftime.

The coated granular pesticide (C.G.P.) mixture Nos. 4 to 6 are mixturesof the coated granular pesticide (C.G.P.) Nos. 43 and 44 (they bothcomprise the pesticide F having an insecticidal effect). Whendetermining the differential release rates of these mixtures, it wasfound that they had release terms after the film-disintegration slightlyshorter than those observed for the C.G.P. mixture Nos. 1 to 3, highpeaks of release rates and they exhibits initial release of traceamounts of active ingredients because of the presence of thewater-soluble active ingredient F, but it was also found that they hadtendencies approximately identical to those observed for the C.G.P.mixture Nos. 1 to 3.

C.G.P. mixture 7 is a mixture of the C.G.P. 41 comprising the pesticideE exhibiting a fungicidal effect and C.G.P. 43 comprising the pesticideF having an insecticidal effect. When examining the accumulated releaserate of the mixture, it was found that the release rate of the mixturehad a tendency almost identical to that observed for C.G.P. 45 (Table12). It was also found that C.G.P. mixture 8 and C.G.P. 46 hadapproximately the same tendency. More specifically, it was found thatalmost the same effect could be obtained using either a coated granularpesticide produced by coating a granular pesticide which comprisedactive ingredients (active ingredients E and F) different in the effectsuch as the granular pesticide J, or a mixture comprising coatedgranular pesticides different from one another in the effect such as thecoated granular pesticide mixture Nos. 7 and 8. In order to cope withvarious kinds of field crops, it is rather preferred to arbitrarilycombine coated granular pesticides having different effects in such amanner that any desired effects can be obtained because of easyhandling.

C.G.P. mixture 9 is a mixture whose ingredients are blended in such amanner that they can continuously release active ingredients havingfungicidal effects and can release active ingredients havinginsecticidal effects at the later half of the growing period of fieldcrops, and C.G.P. mixture 10 is a mixture whose ingredients are blendedin such a manner that they can release active ingredients havinginsecticidal effects at the early half of the growing period of fieldcrops.

Test 1 for Confirming Effect of Coated Granular Pesticide Mixture

A miniature paddy field of 1/2000a was provided in a Wagner pot andthree young seedlings were transplanted to the pot to thus cultivatepaddy rice (cv. Hinohikari). This cultivation of the paddy rice wascarried out according to the currently used cultivation method exceptthat the depth of water upon the transplantation was set at 3 cm. Inthis cultivation method, the active ingredients were used according tovarious methods of application and the effects the reof were evaluated.The active ingredients were used in the cultivation according to thefollowing three methods:

Application Method A (AM: A):

A method comprises the steps of applying 0.1 g of a coated granularpesticide mixture and 0.1 g of a commercially available granularpesticide (containing 4% of the active ingredient E used in the granularpesticide H) to the side furrows of the rice seedlings simultaneouslywith the transplantation of the seedlings and then covering them withsoil immediately after the application.

Application method B (AM: B):

A method comprises the steps of sowing seeds in a nursery box, growingto young seedlings, applying a coated granular pesticide mixture and theforegoing commercially available granular pesticide to the nursery boxat this stage, wherein the amounts of these granules were adjusted sothat they are equal to those used in the application method A, and thentransplanting the young seedlings to a Wagner pot.

Application Method C (AM: C):

A method wherein young seedlings were transplanted without applicationof the coated granular pesticide mixture and the foregoing commerciallyavailable granular pesticide at all.

The coated granular pesticides (C.G.P.) 1 to 3 each was used accordingto the application methods A and B and the seedlings were examined fortheir growing conditions. As a control test division, the applicationmethod B was carried out without using any coated granular pesticide andthe application method C was separately carried out as a treatment-freedivision, to thus examine the seedlings for their growing conditions.The results thus obtained are listed in Table 13.

                  TABLE 13                                                        ______________________________________                                                      Results of Examination                                          ______________________________________                                        C.G.P.    AM: A     There was not observed any lesion                           Mixture 1  and chemical injury throughout the                                   growing period.                                                              AM: B There was not observed any lesion                                        and chemical injury throughout the                                            growing period.                                                             C.G.P. AM: A There was not observed any lesion                                Mixture 2  and chemical injury throughout the                                   growing period.                                                              AM: B There was not observed any lesion                                        and chemical injury throughout the                                            growing period.                                                             C.G.P. AM: A There was not observed any lesion                                Mixture 3  and chemical injury throughout the                                   growing period.                                                              AM: B There was not observed any lesion                                        and chemical injury throughout the                                            growing period.                                                           Control Division                                                                              There was not observed any lesion                               (applied to immediately after the                                             nursery box) transplantation, but there were                                   observed a large number of lesions                                            after 7 weeks from the                                                        transplantation.                                                             Untreated In each pot, there were observed a                                  Division large number of lesions immediately                                   after the transplantation.*                                                ______________________________________                                         *: Any chemical injury was not observed at all.                          

The data listed in Table 13 clearly indicate that the use of C.G.P.mixtures 1 to 3 by the side furrow-application (AM: A) or nurserybox-application (AM: B) permits the effective control of the leaf blastand the head blast through the application thereof only one time.

Paddy Field-Application Test 1

This paddy field-application test was carried out using samples ofC.G.P. 51 to 55 (Table 7) produced by the foregoing PoductionExperiments and C.G.P. mixture 11 to 16 produced by the foregoingProduction Experiments.

To a Wagner pot of 1/5000a, there were added 2.5 kg of the paddy soil(collected from Minamata-Shi, Kumamoto-Ken, Japan) on which a largequantity of wild barnyard millet had grown and then water. After the potwas allowed to stand for one day, water was further added so as to be adepth of water (distance from the level of the soil to the surface ofwater) was 5 cm to thus establish conditions for a paddy field. In thisrespect, the thickness of the soil layer as measured from the bottom ofthe pot was found to be 10 cm. Three rice seedlings (cv. Hinohikari)which had been raised in a nursery box in advance were transplanted toeach pot and 0.1 g of each sample granule was applied thereto.Separately, the granular pesticide (G.P.) F free of any coating wasapplied to the pot so that the application amount of the activeingredient was equal to that of each sample (Comparative Example 2).After the transplantation, the cultivation was carried out whileappropriately supplementing water so as to compensate the reduced amountthereof. The cultivation was continued over 10 days and the seedlingswere inspected for the presence of any chemical injury. The results thusobtained are summarized in Table 14.

Paddy Field-A--lication Test 2

Subsequent to the paddy field-application test 1, the rice plants werereaped at 10 days after the transplantation, followed by allowing thepots to stand without altering the other conditions over 40 days afterthe transplantation to observe growth of weeds and to thus evaluate thesustained effects of the granular pesticides. The results thus obtainedare also listed in Table 14.

                  TABLE 14                                                        ______________________________________                                        Sample      Chemical Injury                                                                              Growth of Weeds.sup.1)                             ______________________________________                                        Comp.  G.P. F   Observed.      Weeds severely                                   Ex. 2  The rice seedlings grew.                                                 were withered within                                                          10 days.                                                                    Ex. C.G.P. Only slight chemical Weeds slightly                                47 51 injury was observed. grew.                                                The plant was                                                                 slightly undergrown.                                                        Ex. C.G.P. No chemical injury Weeds moderately                                48 52 was observed. grew.                                                     Ex. C.G.P. No chemical injury Weeds severely                                  49 53 was observed. grew.                                                     Ex. C.G.P. No chemical injury Weeds severely                                  50 54 was observed. grew.                                                     Ex. C.G.P. No chemical injury Weeds slightly                                  51 55 was observed. grew.                                                     Ex. C.G.P. No chemical injury Weeds did not                                   52 Mx. 11 was observed. grow at all.                                          Ex. C.Q.P. No chemical injury Weeds did not                                   53 Mx. 12 was observed. grow at all.                                          Ex. C.G.P. No chemical injury Weeds did not                                   54 Mx. 13 was observed. grow at all.                                          Ex. C.G.P. No chemical injury Weeds did not                                   55 Mx. 14 was observed. grow at all.                                          Ex. C.G.P. No chemical injury Weeds did not                                   56 Mx. 15 was observed. grow at all.                                          Ex. C.G.P. No chemical injury Weeds did not                                   57 Mx. 16 was observed. grow at all.                                        ______________________________________                                         .sup.1) Weeds: Wild Barnyard Millet.                                     

As seen from the results listed in Table 14, the granular pesticide(G.P.) F (free of any coating) caused chemical injury, while C.G.P. 51caused only slight chemical injury, C.G.P. Nos. 52 to 55 and C.G.P.mixture Nos. 11 to 16 did not cause any chemical injury and theseedlings satisfactorily grew. This clearly indicates that if thetransplantation of seedlings and the application of a herbicide arecarried out at the same time, the release of the active ingredientsshould be inhibited over a certain period. It has been proved that theuse of the coated granular pesticides according to the present inventionsuch as C.G.P. Nos. 51 to 55 and C.G.P. mixture. Nos. 11 to 16 is quiteeffective for this purpose.

G.P. F and C.G.P. Nos. 51 to 55 showed herbicidal effect orweed-growth-inhibitory effect till the 30th day after thetransplantation, but wild barnyard millet grew on the 40the daythereafter. This clearly indicates that the foregoing granules have anonly slight residual activity. The quantity of wild barnyard milletdeveloped was remarkable, in particular, when C.G.P. Nos. 53 to 54 wereused. When using C.G.P. mixture Nos. 11 to 16, wild barnyard millet didnot grow at all or scarcely grew. Therefore, it would be clearly provedthat these granules showed a residual activity. These mixtures exhibitedweed-growth-inhibitory effect even on and after the 40th day.

Paddy Field-Aoplication Test 3

The test was performed under the same conditions used in the foregoingpaddy field-application tests 1 and 2 except that any rice seedling wasnot transplanted at the same period and further the opening of the potwas covered with a polyvinylidene chloride wrap to prevent theevaporation of water. The aqueous solution was periodically sampled fromthe center of the aqueous phase and the sample was inspected for theamount of the active ingredient. The average water temperature duringthe test period was 20° C. and the analysis was carried out over 40 daysafter the application of the pesticides. At the same time, C.G.P. Nos.51 to 55 were also tested. As typical examples, the change in theconcentration of the active ingredient of C.G.P. 55 present in the wateris shown in FIG. 7 and those observed for C.G.P. mixture Nos. 11 to 16are shown in FIG. 8.

The data plotted on FIG. 7 indicate that C.G.P. 55 is an earlyrelease-initiation type coated granular herbicide, it is confirmed thatthe release of the active ingredient is inhibited for 3 days andthereafter the active ingredient is rapidly released and discharged inwater. In addition, the concentration of the active ingredient isreduced on the 20th day after the application of the granule and thus itwould be assumed that the granule would lose the efficacy. The resultsshown in FIG. 8 clearly indicate that C.G.P. mixture Nos. 11 to 16permit the maintenance of each active ingredient's concentration to adesired level and the efficacy thereof lasts over a long period of time,although the amount of each C.G.P. mixture 11 to 16 is identical tothose of the G.P. F and C.G.P. Nos. 51 to 55.

Test 3 for Release in Water

C.G.P. 47 and 48 (Table 6) produced in the foregoing ProductionExperiments were subjected to tests for examining the release of theactive ingredients in water. There were added, to a beaker, 1000 ml ofdistilled water and 0.1 g of each C.G.P. and each C.G.P. was inspectedfor the film disintegration conditions with the lapse of time. Inaddition, the distilled water in the beaker was periodically sampled,followed by analyzing the hardly water-soluble active ingredientspresent in the sampled distilled water using high performance liquidchromatography and detection of the peak to thus determine the releaseinitiation time. The water temperature during the determination was setat 25° C. and the determination was carried out over 28 days after theapplication of the granule. The results obtained are summarized in thefollowing Table 15.

Test 4 for Release in Water

C.G.P. 49 and 50 produced in the foregoing production experiments weresubjected to tests for examining the release of the active ingredientsin water. There were added, to a beaker, 500 ml of distilled water and 1g of each C.G.P. and each C.G.P. was inspected for the filmdisintegration conditions with the lapse of time. In addition, thedistilled water in the beaker was periodically sampled, followed byanalyzing the hardly water-soluble active ingredients present in thedistilled water thus sampled using high performance liquidchromatography and detection of the peak to thus determine therelease-initiation time. The water temperature during the determinationwas set at 25° C. and the determination was carried out over 35 daysafter the application of the granule. The results obtained are alsosummarized in the following Table 15.

                  TABLE 15                                                        ______________________________________                                                              Release-Initiation                                        Sample Time (Day)                                                           ______________________________________                                        Example 58    C.G.P. 47   20th                                                  Example 59 C.G.P. 48 20th                                                     Example 60 C.G.P. 49 30th                                                     Example 61 C.G.P. 50 18th day after the                                         application                                                               ______________________________________                                    

Production of Substrate for Raising Seedlings

Substrate 1 for Raising Seedlings

To a concrete mixer, there were added a mixture of 2900 g of diluvialvolcanic ash soil (maximum water-holding capacity: 120%; particle size:not more than 2 mm) and 100 g of vermiculite (particle size: not morethan 10 mm) as a water-holding material (3000 g in total); compoundfertilizer (N-P₂ O₅ -K₂ O=13-13-13, Chisso Corporation, trade name:Kumiai Ryuukarinan No. 11) in such an amount that the amounts of N, P₂O₅ and K₂ O each was equal to 1 g, as a fertilizer for raisingseedlings; and 50 g of C.G.P. 47 produced in the foregoing productionexperiment, followed by admixing these ingredients till a uniformmixture was obtained to give a substrate for raising seedlings of apaddy rice.

Substrate 2 for Raising Seedlings

The same procedures used for preparing the substrate 1 for raisingseedlings except for using a blend containing 50 g of coated compoundfertilizer (N-P₂ O₅ -K₂ O=14-12-14, Asahi Chemical Industry Co., Ltd.,trade name: Long 424) and Ryuukarinan as a quick-acting fertilizer forraising seedlings in such an amount that the amounts of N, P₂ O₅ and K₂O each was equal to 1 g, in place of the fertilizer used in thesubstrate 1 to thus give a substrate for raising seedlings of a paddyrice.

Substrate 3 for Raising Seedlings

To a concrete mixer, there were added 3000 g of diluvial volcanic ashsoil (maximum water-holding capacity: 120%; particle size: not more than2 mm) as a water-holding material and Ryuukarinan as a quick-actingfertilizer for raising seedlings in such an amount that the amounts ofN, P₂ O₅ and K₂ O each was equal to 1 g, followed by admixing theseingredients till a uniform mixture was obtained to thus give a substratefor raising seedlings of a paddy rice.

Substrate 4 for Raising Seedlings

To a concrete mixer, there were added 3000 g of diluvial volcanic ashsoil (maximum water-holding capacity: 120%; particle size: not more than2 mm) as a water-holding material and compound fertilizer (N-P₂ O₅ -K₂O=13-13-13, Chisso Corporation, trade name: Kumiai Ryuukarinan No. 11)as a fertilizer for raising seedlings in such an amount that the amountsof N, P₂ O₅ and K₂ O each was equal to 1 g, followed by admixing theseingredients till a uniform mixture was obtained to thus give a substratefor raising seedlings of a paddy rice.

Substrate 5 for Raising Seedlings

To a concrete mixer, there were added 3000 g of diluvial volcanic ashsoil (maximum water-holding capacity: 120%; particle size: not more than2 mm) as a water-holding material, compound fertilizer (N-P₂ O₅ -K₂O=13-13-13, Chisso Corporation, trade name: Kumiai Ryuukarinan No. 11)as a fertilizer for raising seedlings in such an amount that the amountsof N, P₂ O₅ and K₂ O each was equal to 1 g and 50 g of the coatedgranular pesticide 48 produced in the foregoing Production Experiment,followed by admixing these ingredients till a uniform mixture wasobtained to thus give a substrate for raising seedlings of a paddy rice.

Substrate 6 for Raising Seedlings

A substrate for single cell transplanting, "Yosaku N-150" (KyushuChemical Industry Co., Ltd.), comprising vermiculite and peat-moss asprincipal components was used as the water-holding material. Thiswater-holding material has such physico-chemical properties as anapparent specific gravity of 0.38 kg/L, a pH value (1:5 water) of 6.7,an electric conductivity (EC) (1:5 water) of 0.7 mS/cm and a watercontent of 30% and the contents of fertilizer components are 150 mg/L ofN, 1000 mg/L of P₂ O₅ and 150 mg/L of K₂ O. Among these, all of theammonium nitrogen is originated from acetaldehyde-condensed urea (CDU).Furthermore, it also comprised citric acid-soluble MnO and B₂ O₃ inamounts of 0.2 mg/kg and 0.05 mg/kg, respectively.

A 9 cm plastic pot (having inner volume of about 300 ml) was filled withthe mixture containing the water-holding material, followed by applying1 g of C.G.P. 49 produced in the foregoing production experiment on themixture and then stirring it to give a substrate for vegetable.

Substrate 7 for Raising Seedlings

A water-holding material was produced by a vermiculite-substrate forhorticulture, "Yosaku No. V1" (Kyushu Chemical Industry Co., Ltd.),comprising vermiculite and peat-moss as principal components, anddisinfected diluvial volcanic ash soil (maximum water-holding capacity:120%; particle size: not more than 2 mm) in a volume ratio of 1:3 andthen uniformly mixing these ingredients. This vermiculite-substrate forhorticulture has such physico-chemical properties as an apparentspecific gravity of 0.35 kg/L, a pH value (1:5 water) of 6.8, an ECvalue (1:5 water) of 1.3 mS/cm and a water content of 30% and thecontents of fertilizer components are 500 mg/L of N, 4400 mg/L of P₂ O₅and 400 mg/L of K₂ O. In this respect, 300 mg/L of the nitrogen isoriginated from acetaldehyde-condensed urea (CDU) and 200 mg/L of theammonium nitrogen. Furthermore, it also comprised citric acid-solubleMnO and B₂ O₃ in amounts of 0.2 mg/kg and 0.05 mg/kg, respectively.

A 9 cm plastic pot (having inner volume of about 300 ml) was filled withthe mixed soil, followed by applying 1 g of C.G.P. 49 produced in theforegoing Production Experiment on the mixed substrate and then stirringit to give a substrate for vegetable.

Substrate 8 for Raising Seedlings

A substrate for vegetable growing was produced by the same proceduresused in the production of the substrate 7 for raising seedlings exceptthat there was applied, to the substrate 7 for raising seedlings, 1 g ofa coated compound fertilizer, "Micro Long Total 201-100" (Asahi ChemicalIndustry Co., Ltd.) and that the resulting mixture was then uniformlystirred.

Substrate 9 for Raising Seedlings (Comparative)

Disinfected diluvial volcanic ash soil (maximum water-holding capacity:120%; particle size: not more than 2 mm) was used and fertilizercomponents were added so that each pot comprised 150 mg/L of N, 1000mg/L of P₂ O₅ and 150 mg/L of K₂ O. Micro elements included therein werewater-soluble MnO and B₂ O₃ whose contents were 0.2 mg/kg and 0.05mg/kg, respectively.

A 9 cm plastic pot (having inner volume of about 300 ml) was filled withthe foregoing mixture containing the water-holding material to give asubstrate for vegetable.

Substrate 10 for Raising Seedlings

A substrate for vegetable was produced according to the same proceduresused for producing the substrate 6 for raising seedlings except thatC.G.P. 49 was not incorporated into the substrate.

Substrate 11 for Raising Seedlings

A substrate for single cell transplanting, "Yosaku N-100" (KyushuChemical Industry Co., Ltd.), comprising vermiculite, peat-moss andperlite as principal components was used as the water-holding material.This water-holding material has such physico-chemical properties as anapparent specific gravity of 0.38 kg/L, a pH value (1:5 water) of 6.3,an EC value (1:5 water) of 0.5 mS/cm and a water content of 40% and thecontents of fertilizer components are 100 mg/L of N, 500 mg/L of P₂ O₅and 100 mg/L of K₂ O. Among these, all of the nitrogen is originatedfrom acetaldehyde-condensed urea (CDU). Furthermore, it also comprisedcitric acid-soluble MnO and B₂ O₃ in amounts of 0.2 mg/kg and 0.05mg/kg, respectively. In addition, 2 g of C.G.P. 50 produced in theforegoing production experiment was applyed on the mixture and then themixture was stirred to give a substrate for flowers and ornamentalplants.

Substrate 12 for Raising Seedlings

A substrate for flower growing was produced according to the sameprocedures used for producing the substrate 11 for raising seedlingsexcept that C.G.P. 50 was not incorporated into the substrate.

Raising Seedling Test

Example 62

The substrate 1 for raising seedlings (2000 g) was introduced into anursery box, followed by smoothing the surface of the substrate anduniformly sowing 150 g of rice seeds of a paddy rice (cv. Hinohikari) inthe substrate. Moreover, the seeds were covered with 1000 g of the samesubstrate. Thereafter the nursery boxes were placed in a glasshouse(Tobata-Ku, Kitakyushu-Shi, Fukuoka-Ken, Japan) to thus grow youngseedlings. The cultivation management was performed by appropriatelywatering to prevent drying of the superficial layer of the substrate andcarrying out additional manure two times, i.e., applying 0.5 g each (asexpressed in terms of the amount of N) of the foregoing Ryuukarinan(twice) per nursery box. Other management for raising seedlings wascarried out according to the methods currently used.

Example 63

A raising seedling test was carried out according to the same proceduresused in Example 62 except that the substrate 2 for raising seedlings wassubstituted for the substrate 1 for raising seedlings and that theadditional manure was omitted.

Example 64

The substrate 3 for raising seedlings (2000 g) was introduced into anursery box, followed by smoothing the surface of the substrate anduniformly sowing the substrate with a mixture comprising 150 g of riceseeds of a paddy rice (cv. Hinohikari) and 600 g of coated urea (N-P₂ O₅-K₂ O=40-0-0, Chisso Corporation, trade name: LP Coat S100) showingsigmoid type fertilizer-release characteristics. The soil cover used wasa composition produced by uniformly mixing 1000 g of the same substratewith 50 g of C.G.P. 47 produced in the foregoing Production Experiment.Thereafter the nursery boxes were placed in the same glasshouse used inExample 62 to thus grow young seedlings. The cultivation management wasperformed by appropriately watering to prevent drying of the superficiallayer of the substrate and additional manure was omitted. Othermanagement for raising seedlings was carried out by the same proceduresused in Example 62.

Comparative Example 3

A substrate (2000 g) produced by uniformly mixing 3000 g of thesubstrate 4 for raising seedlings with 34.5 g of the granular pesticideK produced in the foregoing poduction experiment was introduced into anursery box, followed by smoothing the surface of the substrate anduniformly sowing 150 g of rice seeds of a paddy rice (cv. Hinohikari) inthe substrate. The same substrate (1000 g) was used as the soil cover.Thereafter the nursery boxes were placed in the same glasshouse used inExample 62 to thus grow young seedlings. The cultivation management wasperformed by appropriately watering to prevent drying of the superficiallayer of the substrate and carrying out additional manure two times,i.e., applying 0.5 g each (as expressed in terms of the amount of N) ofthe foregoing Ryuukarinan (twice) per nursery box. Other management forraising seedlings was carried out by the same procedures used in Example62.

Example 65

The substrate 5 for raising seedlings (2000 g) was introduced into anursery box, followed by smoothing the surface of the substrate anduniformly sowing 150 g of rice seeds of a paddy rice (cv. Hinohikari) inthe substrate. Moreover, the seeds were covered with 1000 g of the samesubstrate 5. Thereafter the nursery boxes were placed in the sameglasshouse used in Example 62 to thus grow young seedlings. Thecultivation management was performed by appropriately watering toprevent drying of the superficial layer of the substrate and carryingout additional manure two times, i.e., applying 0.5 g each (as expressedin terms of the amount of N) of the foregoing Ryuukarinan (twice) pernursery box. Other management for raising seedlings was carried outaccording to the currently used method.

Comparative Example 4

The substrate 4 for raising seedlings was introduced into a nursery boxand the granular pesticide L produced in the foregoing productionexperiments was applied to the substrate in the nursery box immediatelybefore transplantation of seedlings according to the currently usedmethod. Thereafter the nursery boxes were placed in the same glasshouseused in Example 62 to thus grow young seedlings. The cultivationmanagement was performed according to the currently used method.

Triplicate divisions treated according to each method disclosed inExample 62 to 65 or Comparative Example 3 or 4 were examined forchemical injury during the seedling-raising term. The results thusobtained are listed in Table 16.

                  TABLE 16                                                        ______________________________________                                        Sample                                                                          (Substrate                                                                    for Day after sowing (Day)                                                  Raising)     1       3       7     14    21                                   ______________________________________                                        Ex. 62 1         ---     ---   ---   ---   ---                                  Ex. 63 2 --- --- --- --- ---                                                  Ex. 64 3 --- --- --- --- ---                                                  Ex. 65 5 --- --- --- --- ---                                                  Comp. 4 --- ±±± ±±± +++ +++                                 Ex. 3                                                                         Comp. 4 --- --- --- --- ---                                                   Ex. 4                                                                       ______________________________________                                    

-: Any chemical injury was not observed.

±: There was observed slight chemical injury, but any practical problemdid not arise.

+: There was observed chemical injury.

As seen from the results shown in Table 16, seedlings couldsatisfactorily be raised in Examples 62 to 65 and Comparative Example 4without causing any chemical injury. In Comparative Example 3, agrowth-inhibitory effect was observed shortly after the application ofthe pesticide and it has thus been proved that the seedlings weredamaged from the pesticide and that the formulation prepared by such aconventional method is not favorably used as a substrate for raisingseedlings of a paddy rice. Moreover, it was also confirmed that goodseedlings could satisfactorily be raised without being damaged from thepesticide during the raising term in Example 65 wherein a differentactive ingredient was used.

Paddy Rice Cultivation Test I

Young seedlings of a paddy rice were raised over 3 weeks according tothe procedures disclosed in either of Examples 62 to 64 and ComparativeExample 3 and then the young seedlings were transplanted to andcultivated in each Wagner pot of 1/2000a at a rate of three seedlingsper pot. The cultivation was carried out according to the currently usedmethod except that the depth of water upon the transplantation was setat a level of 3 cm. Regarding the test divisions of Comparative Example3, the granular pesticide K was applied thereto on the 7the day afterthe transplantation.

As a result, the observation of the seedlings throughout the cultivationterm proved that the efficacies of the active ingredients observed inExamples 62 to 64 were identical to or superior to that observed inComparative Example 3 and that barnyard millet at its bifoliate periodwas controlled in both Examples 62 to 64 and Comparative Example 3. Inparticular, the seedlings in Example 64 did not require any additionalmanure during the cultivation period. Accordingly, this wouldconsiderably contribute to the reduction of labor required forapplication of pesticides and/or fertilizers.

Paddy Rice Cultivation Test II

Young seedlings of a paddy rice were raised over 3 weeks according tothe procedures disclosed in either of Example 65 and Comparative Example4 and then cultivation tests were carried out using 30 bundles (3stocks/bundle) selected from 5 among the foregoing nursery boxes. In thetests, the transplantation and cultivation were carried out using Wagnerpots of 1/5000a under paddy conditions (depth of water: 3 cm).

As a result, there was observed irregularity in the efficacy of thegranular pesticide L in Comparative Example 4 and part of the leaveswere damaged from the active ingredient of the pesticide L adheredthereto. This fact proves that it is difficult to uniformly apply thegranular pesticide L as a conventional pesticide on the nursery boxescomprising seedlings of paddy rice which has grown to some extent andwhose leaves have grown thick. Both Example 65 and Comparative Example 4exhibited sufficient efficacies and, in particular, Example 65 showed aduration of efficacy longer than that observed in Comparative Example 4.

Test for Confirming Effects Using Cucumber

A test for raising seedling and cultivation of cucumber (cv. KinseishiyoNo. 2; "KURUME GENSHU IKUSEI KAI (Society of Kurume-Foundation StockGrowth)") was carried out using the substrates 6 to 10 for raisingseedlings as substrate for vegetable. The raising seedlings and thecultivation thereof were carried out in a glasshouse (Tobata-Ku,Kitakyushu-Shi, Fukuoka-Ken, Japan) and the management for raising ofseedlings and cultivation thereof was carried out according to themethods currently used.

In every test divisions other than the substrate 8 for raisingseedlings, additional manure was carried out several times during theraising of seedlings. The raising seedlings was terminated after 30 daysand then the seedlings were transplanted to Wagner pots of 1/2000afilled with disinfected diluvial volcanic ash soil. The substrate 10 forraising seedlings was subjected to the hole treatment according to thecurrently used method using 1 g of kneaded granules containing 2% of anactive ingredient (pesticide C). The test was carried out four timesusing 3 stocks per each test division and each test division wasobserved and examined. The results thus obtained are summarized in thefollowing Table 17.

                  TABLE 17                                                        ______________________________________                                                    Examination of                                                       Plant                                                                        Sample (after 2 weeks) Status After 3 Weeks                                 (No. of     Length   No. of   from the Transplantation                          Substrate) (cm) Leaves of Seedlings                                         ______________________________________                                        Ex. 66 7        19.2     2.5    There was not observed                              any chemical injury;                                                          there was not observed                                                        any breeding of aphids.                                                   Ex. 67 8 21.5 2.5 There was not observed                                          any chemical injury;                                                          there was not observed                                                        any breeding of aphids.                                                   Ex. 68 9 22.0 2.5 There was not observed                                          any chemical injury;                                                          there was not observed                                                        any breeding of aphids.                                                   Comp. 10 19.5 3.0 There was observed the                                      Ex. 5    breeding of aphids.                                                  Comp. 11 20.8 3.0 There was not observed                                      Ex. 6    any chemical injury;                                                     there was not observed                                                        any breeding of aphids.                                                 ______________________________________                                    

As seen from the results listed in Table 17, the substrates 6 to 8 forraising seedlings permitted satisfactory raising and cultivation ofseedlings without causing any damage from the pesticide throughout thecultivation period including that required for raising the seedlings. Onthe other hand, in case of the substrate 9 for raising seedlings, aphidscame flying immediately after the transplantation and the seedlingssuffered from disease injury. There were observed dead aphids in thevicinity of the stocks transplanted to the substrates 6 to 8 and 10 andaccordingly, the efficacies of the pesticides would be sufficient inthese substrates.

In addition, there was observed a tendency of suffering from microelement (iodine)-excess symptom on the seedlings transplanted to thesubstrate 9. This would be caused due to the water-solubility of themicro element, but the excess symptom could be ignored from theviewpoint of cultivation.

The substrates 6 to 8 can eliminate the use of the hole treatment andtherefore, the transplantation operation of the seedlings required onlya short period of time. The substrate 10 required a great deal of laborsince the substrate 10 required the use of the hole treatment and theuse of this substrate further required additional operations forweighing and applying the granular pesticide in addition to theoperations required for digging holes.

Effect-Confirmation Test Using Chrysanthemum

Tests for raising seedlings of chrysanthemum and for cultivating thereofwere carried out using the substrates 11 and 12 for raising seedlings.The chrysanthemum to be tested (cv. Oki No Shiranami) was subjected toherbaceous cutting in a cell tray (circular connected tray having anupper diameter of 23 mm, a bottom diameter of 18 mm, a depth of 35 mmand a volume of 12 ml) and the seedlings were raised under the lightingconditions. The raising seedlings and the cultivation thereof werecarried out in a glasshouse (Tobata-Ku, Kitakyushu-Shi, Fukuoka-Ken,Japan) and the management of the raising seedlings and the cultivationthereof were performed according to the currently used methods. In everytest divisions, additional manure was carried out several times duringthe raising seedlings. The raising seedlings was terminated after 2weeks at which the roots of the seedlings had grown to densely fill thesubstrate in the cell and then the seedlings were transplanted to Wagnerpots of 1/2000a filled with disinfected diluvial volcanic ash soil (thepH value thereof was adjusted to 6.3). The substrate 13 for raisingseedlings was subjected to the hole treatment according to the currentlyused method using 2 g of kneaded granules (containing 0.5% by weight ofan active ingredient of the pesticide C). The cultivation test wascarried out four times using 3 stocks per each test division and eachtest division was observed and examined. The results thus obtained aresummarized in the following Table 18.

                  TABLE 18                                                        ______________________________________                                               Substrate                                                                for                                                                           Raising                                                                       Seedling Results Observed after One Week                                      No. from the Transplantation                                                ______________________________________                                        Example  12         There was not observed any damage                           69  from pesticide. Aphids were                                                 exterminated.                                                               Comp. 13                                                                      Example  There was not observed any damage                                    7  frorn pesticide. Aphids were                                                 exterminated.                                                             ______________________________________                                    

As will be clear from the results listed in Table 18, the substrate 11for raising seedlings permitted satisfactory raising and cultivation ofseedlings without causing any damage from the pesticide through out thecultivation period including that required for raising the seedlings.There were observed dead aphids in the vicinity of the stockstransplanted to the substrates 11 to 12 and accordingly, the efficaciesof the pesticides would be sufficient in these substrates. The substrate11 did not require the use of the hole treatment and the seedlings wereraised in a cell tray filled with the substrate 11. Therefore, thetransplantation operation of a large number of the seedlings requiredonly a short period of time and this results in a substantial reductionof labor. The substrate 12 required a great deal of labor since thesubstrate 12 required the use of the hole treatment and the use of thissubstrate further required additional operations for weighing andapplying the granular pesticide in addition to the operations requiredfor digging holes.

Effects of the Invention

As has been explained above in detail, the coated granular pesticideaccording to the present invention can initiate the release of theactive ingredient of the pesticide after the lapse of a predeterminedtime, since a film of a thermoplastic resin is formed on the surface ofa granular pesticide which comprises a hardly water-soluble activeingredient and a water-swelling substance. More specifically, thefollowing effects can be accomplished by the present invention.

(1) The conventional pesticide comes in contact with the environmentalwater simultaneous with the application thereof and therefore, itinitiates the release of the active ingredient thereof immediately afterthe application. On the other hand, the coated granular pesticide of thepresent invention permits the inhibition of the release of the hardlywater-soluble active ingredient of the pesticide over a predeterminedperiod of time.

(2) The conventional coated granular pesticide releases the activeingredient of the pesticide through migration of water while making useof the permeability of the film instead of making use of thedisintegration of the film. Accordingly, such conventional technique isnot effectively applied to pesticides comprising hardly water-solubleactive ingredients. Contrary to this, the coated granular pesticide ofthe present invention permits the external release of the activeingredient through the disintegration of the film due to the co-operatedinteraction of the water permeability of the film and the water-swellingproperties of the water-swelling substance present in the granularpesticide. For this reason, the present invention permits the use ofhardly water-soluble active ingredients and thus the present inventioncan make the range of choice of usable active ingredients more wider.

(3) The coated granular pesticide of the present invention permits therelease of the granular pesticide containing the hardly water-solubleactive ingredient through the disintegration of the film thereof.Therefore, the pesticide does not result in the reduction of the releaserate as the concentration on the active ingredient in the aqueoussolution within the film is reduced and the active ingredient does notremain within the film over a long time period, unlike the conventionalcontrolled release type coated granular pesticides, and the coatedpesticide of the present invention can completely release the hardlywater-soluble active ingredient, ensure a high utilization factor and isnot accompanied by any danger due to residues. Moreover, the presentinvention also permits the reduction of the amount of the hardlywater-soluble active ingredient to be used.

(4) The use of a mixture of at least two coated granular pesticideswhich differ in the release-inhibitory period permits the sustainedrelease of required active ingredients over a long period of timedepending on the kinds of field crops.

(5) The present invention can inhibit the appearance of any peak of thereleased active ingredient and accordingly, can prevent any damage offield crops from the pesticide due to temporary excess release of theactive ingredient.

(6) The conventional insecticides and/or fungicides must be applied tofield crops several times during the whole growth period thereof, whileif the coated granular pesticide mixture of the present invention isused, any desired effect can be obtained by a single application thereofto the crops and the present invention can thus further reduce laborrequired for farm working. With respect to the paddy rice, inparticular, both leaf blast and head blast can be controlled by a singleapplication of the foregoing mixture.

(7) In the present invention, it is very easy to control the releaserate of the active ingredient by appropriately selecting components tobe added to the film.

(8) The substrate for raising seedlings according to the presentinvention which can be prepared by admixing the coated granularpesticide, a water-holding material and optionally a fertilizer or thelike can easily be handled, is effective for the reduction of laborrequired for farm working and is quite useful as substrates for raisingseedlings of paddy rice and substrates for raising seedlings used forother agricultural and/or horticultural purposes.

What is claimed is:
 1. A coated granular pesticide, said coated granularpesticide comprising at least one hardly water-soluble active ingredientand at least one water-swelling substance which have been mixed togetherand then formed into granules, the surface of said granular pesticidebeing coated with a film whose principal component is a thermoplasticresin,wherein said thermoplastic resin is selected from the groupconsisting of at least one polyolefin, an olefinic copolymer includingolefin monomers, and mixtures thereof.
 2. The coated granular pesticideas set forth in claim 1 wherein an ethylene/vinyl acetate copolymer isincorporated into the film in an amount of not more than 15% by weight.3. The coated granular pesticide as set forth in claim 1 wherein asurfactant is incorporated into the film.
 4. The coated granularpesticide as set forth in claim 1 wherein a thermosetting resin isincorporated into the film.
 5. The coated granular pesticide as setforth in claim 1 wherein a biodegradable polymer insoluble or hardlysoluble in water is incorporated into the film.
 6. The coated granularpesticide as set forth in claim 1 wherein the hardly water-solubleactive ingredient is an active ingredient for pesticide havinginsecticidal and/or fungicidal effects.
 7. The coated granular pesticideas set forth in claim 1 wherein the hardly water-soluble activeingredient is an active ingredient for pesticide having a herbicidaleffect.
 8. The coated granular pesticide as set forth in claim 1 whereinthe film has a single layer structure.
 9. The coated granular pesticideas set forth in claim 1 wherein said pesticide can externally releasethe hardly water-soluble active ingredient thereof according to such amechanism that the water-swelling substance absorbs water from theexternal environment, which gradually penetrates into the activeingredient through the coating film, the granular pesticide containingthe water-swelling substance gradually expands, cracks are thus formedon the film after the elapse of a predetermined time, water rapidlyenters into the active ingredient through the cracks thus formed, theswelling of the water-swelling substance is accelerated to thus greatlygrow the cracks and to thus rapidly disintegrate the film and that thehardly water-soluble active ingredient included in the granularpesticide thus comes in close contact with a large amount of water. 10.A coated granular pesticide, said coated granular pesticide comprisingat least one hardly water-soluble active ingredient and at least onewater-swelling substance which have been mixed together and then formedinto granules, the surface of said granular pesticide being coated witha film whose principal component is a thermoplastic resin,wherein aninorganic powder which is insoluble or hardly soluble in water, isincorporated into the film.
 11. A coated granular pesticides, saidcoated granular pesticide comprising at least one hardly water-solubleactive ingredient and at least one water-swelling substance which havebeen mixed together and then formed into granules, the surface of saidgranular pesticide being coated with a film whose principal component isa thermoplastic resin,wherein at least one of a water absorbing polymerfine powder or water-soluble polymer fine powder is incorporated intothe film.
 12. A coated granular pesticide according to claim 1, whereinsaid mixture of the at least one hardly water-soluble active ingredientand at least one water-swelling substance are mixed so as to form ablend and the blend is then coated with said film.
 13. A coated granularpesticide according to claim 1, wherein said granules are formed byextrusion.
 14. A coated granular pesticide according to claim 1, whereinsaid hardly water-soluble active ingredient and said water-swellingsubstance are mixed together to form a blend in such manner that thepesticide will continuously release active ingredients.